[capt_noonie]

Maybe for his $6000 bikes, yes. But you have to think about what shop you go to. Labor rates can vary dramatically. We only charge $7 to put in a tire or tube. The shop down the street charges $20. Then tires can range from $15 for cheapy no names, up to $100+ for high performance; and the tube itself around $7 each. Then times that by 4 (2 tires on each bike, and 2 bikes).

Simple tune ups are also going to run anywhere from $25-70 depending on what you want done and if you need anything replaced (cables, chains, etc).

If you just want to try out the bikes for a day, see if the tubes will hold any air. It really depends on how long the bikes have been sitting. If it's been more than a few months I would really suggest getting at the very least new tubes. If your brother can help you change them out, then you don't have to pay the labor for the shop to do it for you. But since tubes are rubber, they can dry out. When you inflate a dried out tube, it will create fissures and air will come out.

However, the money you have to pay to get these bikes up and running will be about $100 or more, but remember that $500 will get you ONE new bike with new tires, so if you get two that's $1000.

Maybe you can strike a deal with your friend. Once you give him back his bikes (all newly tuned up with new tires) maybe he can pay you some of it back, maybe 50% since you got them fixed up? Or is he willing to just give you these bikes? If these bikes are in overall good condition (no rust or anything like that) then maybe it might be worth it to keep these old bikes. Check to see if the wheel spin true also (no wobbles). Trueing a rim can cost $20+ each.