Hmm.
Since he is on a limited budget here, and you apparently refuse to pull down the big bucks and keep him in the lifestyle he needs to become accustomed to... (you need to become a CEO of a large corporation)
perhaps its time to sit down and plan a budget for everything.
You two pool your resources to pay rent/mortgage, bills, food, insurance, blah blah blah - perhaps you can approach this as '
Its a new year and I think we need to really buckle down and see where we can save money.' Sorta a new years resolution thing.
The aim here is not to take away his collecting, but to manage your resources to pay for essentials and see what it is exactly there is left over to pursue this hobby.
Gather together all of the bills and whatnot, and set about budgeting for all of that, and see how much is left over for 'luxury' items. like um, vacuum cleaners, vacations, trips, etc.
If you can reach an agreement on allotting X amount per month for his hobby, he may adapt to having a real budget to work with, and save that allotted amount toward larger purchases.
I have no idea how much time you personally have, but perhaps if you take up the interest a little bit and research the subject WITH him, you may find that he has a few gems he can sell or trade up with.
I personally never got the whole 'collecting crap' that isn't used for something. I have a lot of tools, but I use them. I don't have a hundred hammers that ain't used as hammers just to 'have' them. So I can't relate to the collector's motivation here.
I tried a Google search for 'effective collecting' and got back a lot of hits for collecting calling.... So it may be a little more work than a quick web search to find sites that deal with collecting for collections in an effective manner.
There used to be a show about comic books and toys where a person would come in and help sort through massive amounts of garbage - erm, I mean collectables, and help the collector streamline their inventory and actually build up a collection over just buying crap to have it (hoarding?). Perhaps your BF's hobby isn't more along the lines of hoarding instead of collecting and can be streamlines?
One thing about collecting antiques, old stuff, and collectors items is that it IS a way to invest in the future. I find it difficult to believe that the lunch pail I had as a kid now sells for thousands of dollars - but this is how it works, and if I was more careful with my crap as a kid I would have a lunch pail I could sell for several thousand dollars today.... So there is a monetary 'value' and future here.
So today it may look like a waste of money, if done properly this isn't so much a waste as an investment that has potential to pay off big time in the long term.