As a matter of comparison, since DOA5 came on topic:
- Costumes are 2$ each, apart from the collaborations (Falcom, Senran Kagura, Tatsunoko, etc) costumes being 3$ each. SFV costumes are 4$ each.
- Costumes can be bought per pack, usually with around 16 costumes per pack. Usually priced 19$ (regular pack), 28$ (collaboration/special) or 32$ (most of the roster).
- Currently at its fourth season pass, with the fifth one likely announced next month. Each pass is at 93$, including 5 costumes packs, for 78 to 101 costumes. Season pass 3 included a character, season pass 4 is including a stage. (edit: each season pass also includes an exclusive costume, but it's usually just some recolor, so no point in counting that)
I'm not saying one is better than the other, both have lessons to take from each other (DOA6 should have a fight money system, while SFV's costumes are way too expensive and not available in packs), but DOA5 actually is less expensive per costume, it's just that there's tons of them.
Last Round launched with around 400 costumes included by the way, even if it seems not as big since it was its third release with 34 characters, it's still more than USFIV.
It's just interesting to look at this if you want SFV to have season passes for costumes. DOA5's season passes are way too expensive, but you also get a lot more than some costumes every 3 months or so.