i'm not sure if anyone uses eBay on here, but here's what I did:
1) Go to clothing stores to find your correct suit size and also figure out what suit brands/manufactures you like
2) Go on eBay and look for suits in your size from brands that you like
3) Once you get your suit, take it to a tailor to get it fitted correctly
you can seriously get a nice brooks brothers suit for around $40. this might take a little longer than buying from a physical store, but you can really save a lot of money!
dress shirts are also super cheap as well