Let's say we have 3000 dues paying members. If the dues were increased a lousy $20 per year, that would generate $60,000 per year to lease and operate a space. How much do you need?

Forget the fact that you can continue fund raising efforts and operate an actual retail space to make money. How much do you need? Since you aren't looking for profit, it's a very simply break even analysis.

Aren't there any business people here?

If you want it, get it done. If you don't, give it up.