I'd go for a good used bike. Sometimes your local bike shop has deals on used bikes that they've refurbished. You'd probably get allot more use out of that than a 'new' walmart bike, also the bike shop would probably have tuned it correctly and will make sure it fits you properly. If you're on a budget I'd also invest in a few tools and learn how to do general repairs yourself. You can also use this site and others to help you with maintainence & repairs, a good bike repair book helps too. The library can be your best friend if you're on a budget too.. Good luck! A ten mile commute is very do able! Don't forget to factor in the cost of transportation and deduct it from you bike commute and you'll find that the bike/repairs/tools will probably be paying for themselves in a short time..