My chapter was very strict on "tasteful" - but we were lax on length requirements and sleeveless/strapless, we sort of had to be. I"m sure we're not the only chapter that struggled with this - but we were in the middle of michigan with very little shopping options (closest mall was roughly 1.5 hours away) AND we didn't want to force our girls to spend a ton of money.
I was lucky enough to have my great grand big hand me down a dress