Ok, I finally bit the bullet and bought the basic version of FormConnect. You can always upgrade to the Pro version with an in app purchase. It's just the difference in price.
A 20 minutes of fooling around with it review.
It works. The feature set comes nowhere close to Bento, but for a simple database of forms it does the job.
I've seen a few minor glitches like the record list getting messed up when deleting records, but going out and back into the app cleared this up. No show stoppers, just stuff the developer needs to address in later versions.
Designing your own form is relatively intuitive, if you've ever made a form before. The first text field added becomes your record name, so choose carefully. {or maybe it's just the one nearest the top of the form} You can add all the usuals and a few extras: text, date, check box, drop down menu, labels, signatures, photo, image (static like a label), notes (hand written), and some lines for breaking things up.
The signature field works well enough, with the ability to lock the signature afterwards and avoid accidental overwriting.
You can export one or more records in a variety of formats: FMC (native), PDF, XML, HTML, and CSV. These can be sent to DropBox, another app, or emailed. The PDF options appears the be the best choice for sending a copy to a customer (which I assume you want).
Besides the basic alphabetized list you can also tag records. That gives you an alternate way of searching/sorting them. You could, for instance, have borrower names for record names, but tag each record with the items name or ID.
I can see two ways to approach your problem. You can either make new records each time an item is borrowed, naming and/or tagging it with the borrower; or you can make a record for each item and change the record info for that item to reflect who has currently borrowed it. Each has it's advantages and disadvantages.
The first leaves a nice record of past borrowers, with no extra effort, but the database could get large and difficult to manage over time if there is a lot of borrowing going on.
The second limits the database to the number of borrowable items, making it easy to search for a current status of each item, but you'll be constantly erasing signatures and will have no history; unless you add some extra steps to archive each form (perhaps as a PDF) before editing it for the new borrower.
Anyway, that should give you an idea of whether you want to use this app or not.
Good luck.