I do around 20 miles per day commuting to work =100miles
Weekend I do 50 miles to and back from coventry = 100miles.
And your average few miles popping here and there throughout the week.
I put in £30 worth of fuel every week and theres usually still just under a quarter of tank left. Never been on the yellow light when putting this amount of fuel in and doing the above journeys.
300miles you will need a full tank which is around £50. If you drive the car sensibly they can be good on fuel...but if you start racing round it soon goes down.
Reliability - I've owned my car 3 years almost maybe longer. I honestly feel that my car could do a stupid journey and i wouldn't worry, start in the coldest of weathers...never had an issue whatsoever in relation to the engine. Car starts up every day, day in day out. I've done over 700 miles over 3 days in it and it just does the job.
The only issues I've with my car are mainly related to the modifications which I've had done and wear and tear like brakes and pads etc. Only major thing i had to replace was steering rack which cost me around £260 fitted. The parts are generally quite cheap and there are a lot of second hand parts on the market. I don't really have a great paid job... but when there has been something wrong I've never worried, because it is quite cheap to have these cars repaired in my personal experience unless its something major like engine issues or like you say gearbox.
If you look after the car well, it will look after you!
This is what I usually pay regular to get done so you can see what its like to run these cars;
Service: I Have service every year at Honda hQ. Oil change and oil filter costs around £55. I recently had Spark plugs, Oil change, Oil filter, Gearbox oil all done for £140. Spark plugs usually only need changing every 2-3 years. Whenever i get an oil change i always get the gearbox oil changed as in my opinion i think its worth it as it costs nothing essentially to have that piece of mind. Air filter... if you've got an induction kit you can either clean them or replace yourself. Fuel filter and brake fluid also pretty cheap to replace. Money is mainly in the Spark plugs. Fuel filter should really changed 80k and over but is a lifetime filter.
Tyres: Everyone has a budget...I've ran budget tyres, and expensive tyres. Cheapest tyres brand new your looking round £35 a tyre I've had them when times have been tough and they've been absolutely fine... and obviously you can spend what you want on tyres...i currently run Yokohama AD08 R which i paid around £100ish per tyre! Obviously there is a big difference on grip but it just depends what you use the car for.
Brakes - If your running Standard Brakes to buy....front discs are around £80 a pair and rear discs are around £70 a pair and pads your looking £40 for front £30 for rear. You of course would need someone to fit and this would cost extra. For example I had brand padgid new rear pads, discs and callipers fitted at £320.
Clutch - The clutches are pretty strong in these if you was looking to get replaced... You can get a excedy clutch and gearbox oil fitted at £320 at Honda hq. I spoke to Abp motorsport and they say they should be changed at around 70k but this is obviously depending on the car. I've still got original clutch in mine and feels great still... and is on 57000miles. Check when it was last replaced, should be in service book.
Timing Chain - Timing Chain and Guides for Genuine honda chain your looking £480 fitted at honda hq. This again depends on the car they can last well over 100k.
Rust - These cars can rust quite easily underneath so it is worth checking underneath. Due to the age of these cars now the factory underseal wears away and goes to bare metal so is recommended to get undersealed. I got my car fully waxoyled when i bought it for £245 (chassis, underbody, all cavities, frames, box sections, axels and suspension, and door cavities). You only need to do this every 3-5 years. For just the underside of the car (top up after 3-5 years) looking at £125. Well worth the money for piece of mind especially if you keeping vehicle long time.
Things to think about when your buying one;
Millano red - Fades and gets Lacquor peel. I have a millano red ep3, I'm absolutely fine now with the faded paint work, and have not bothered to get it resprayed. I've learned to live with it. However if you think you can just polish it up... don't bother...once you have it mopped you just have to keep waxing to keep the colour up. Black cars, they look great but i had experience whenever i went and looked at one i found your common swirl marks in the paint and also EP3'S chip lots on the bonnet and it looks obvious on the black cars and red cars. Colour wise in my opinion i think the silver actually looks really nice and fresh, and wish i opted for this colour... but of course it is not as striking as the grey,black and red.
Sticking rear callipers - common problem I and my friends have both experienced. Will require replacement callipers and probably discs and pads.
Overall all i can say is its not in my opinion a expensive car to run.. along as you keep on top of things and look after it will be fine. The car is so practical and has a big boot. I've always had german cars in the past and this has honestly been more reliable and cheaper to repair. This also has been a car which i have never got bored of and you can get addicted when modifying. There is so much you can do with these cars and it really will put a smile on your face. It is just doing your checks and make sure you look at plenty of cars. I looked at about 10 cars before i decided to buy mine... it pays to travel and look at cars further way. These cars are shooting up in price, and you can struggle to find them under 100k these days! Some are fetching around 5-7k with 60k on the clock.
When buying my car i actually paid a mechanic to come with me to check the car over... as i know nothing...he took it on a test drive and let me know of anything which would require doing... So this might be something you might want to look into.
Good luck with your search!