I'd say buy a used suit from a reputable brand on eBay, Etsy, or thrift store. Here and AAAC are good places to look as well.
Maybe one from this list? http://putthison.com/post/1454913425/a-loosey-goosey-brand-guide-for-thrifting-suits
A new suit under $200 isn't worth it, IMO.
And as for 42S vs 42R vs 40, just buy whatever fits right. Since you're not very tall, you'll have less room for error for the jacket length. I prefer my jacket to cover my rear,...