They cost money, there's no getting away from that. As said before, they will never be worth what you put into them, but that only matters if you are going to sell it.
I paid quite a bit for my car 5 years ago, but it was a one owner, genuine, solid car so was a really good starting point. I've had some paintwork done already, wheels refurbed, interior trimmed, heater matrix changed and other mechanical issues sorted. It's in for some more paint next month, then later in the year, a full nut and bolt engine bay refurb like Andy had. I reckon when it's finished, it will owe me around £10k. Will it be worth that? No, but where else would I be able to buy a car that looks and drives like brand new, that I know inside out?