I suspect though that apart from a few basic concepts a lot of what you'd learn on Bento wouldn't be that transferrable to something else like Access, let alone anything bigger. So, given Bento is going out of support, unless you've got some specific database task you need to do, it might not be that useful in the long run.
Personally, I'd probably advise spending the money on a basic database theory book and a basic SQL book and then install something like the
MAMP or
Valentina along with
Navicat Essentials or
Sequel Pro. Those together will probably give you a better grounding than just using Bento would.
This also looks quite amusing, although I haven't tried it.
(NOTE: I know suggesting MYSQL to someone as 'first lesson in databases' is rather crazy, but the bare fact is if Bento is on the way out there really isn't that much left on the Mac that isn't SQL based.)