Furner;
It's a great idea, and although I would like to see it, it is full of pitfalls. Others have tried similar 'loaner/rental' type programs to share tools with others, but everyone I've heard of has failed.
Maybe someone from the original AR15 Builder's Squad will speak up, but they tried something similar to this and the jig/tools were damaged by one of the 1st users.
Your main headache will be the logistics. Chasing people to get the stuff back, tracking the shipping status, who gets it next, how long? Those type issues. Its easy to manage with only 3-4 people involved, but if you get 30-40+, then it becomes a major issue.
What if you loan it to someone and they send it back. You inspect it and it looks good, then send it out to the next borrower and refund the deposit to the other user. You get a call from the new borrower saying he just got the package and noticed something was damaged. Is he telling the truth? Was it damaged in shipping? Did the new user damage it? Did the old user damage it and you missed the problem during the inspection? Who are you going to go after for the money? These are the type issues you will run into.
Do you set up rules that only people with 1000+ posts are allowed to borrow? That will cut down on fly-by-nighters, but check the feedback in the Equipment Exchange. Occassionally, long time members have been know to screw others, so its not really an indication of reliablity of the person.
What about deposits/payments. You don't want paypal, since it is possible for the credit card accounts to be charged back. Checks? You'd have to deposit them and wait for them to clear. Same with money orders, except if you require PO money orders, and go down to the PO to cash them.
All that being said, if this was to be undertaken by someone, they would probably have about an initial outlay of $150-200 for the tools. He'd have to charge $25-40 per loan, to cover shipping/insurance and recovery of his investment. Or even $25/wk to give people incentive to return the tools in a timely manner. Or you can make it even more complicated. Borrower is responsible for shipping/insuring the return of tools. Also requires tracking number. You could charge $250 deposit. From this you deduct $30 for 1 week, based on when the tracking number indicates it was delivered. Then charge $5/day for each day after the initial week. Charges acrue until you are provided a tracking number that the items are being returned. Once you receive the parts and assure it is complete and undamaged, refund $250 minus the usage charges. The only problem with this is, again, the amount of time/management involved.
It's a great idea, but difficult to work. I have hard enough time getting tools back from my brother-in-law (2 miles away), let alone a stranger (3,000 miles away).