Okay, I think I'm actually going to need some clarification about the limitation on making simoleons. There are at least two collections that give you a monetary reward upon completion; I only knew about one of them, and was more than prepared to leave it incomplete and buy a statue to polish it off, but I've just discovered a second literally at the end of my test run and now I'm paranoid that there's more. Since this was really only a test, I wasn't able to finish all the collections I intend to aim for in my real file, so as things currently stand I'm worried that I'll accidentally invalidate my playthrough by stumbling across a third, hence the need for some clarification...
(also, as Nikitachi's pointed out, there are some... interesting consequences of not being able to make money in any other way, and I very quickly broke the rule in this test file without necessarily meaning to... at least I know what not to do now!)