Just send in a couple of college kids in ratty clothes into the shop.
Next, unleash your half naked baby to shriek and rampage throughout the racks of elegant suits. Pretend not to notice her sagging diaper while you drool over this adorable little man suit.
To prevent being thrown out of the store, do stop your child from unboxing every single cuff link on the sales counter. You have to have some standards.
When the salesman asks if you have a budget, give him a small figure, and then add "Or just whatever you have on clearance. We're trying to be cheap." Don't be surprised if he says "Yes. I can tell."
Try not to be too disappointed when you learn that the dark gray suit you saw on clearance online is definitely not the same as the tan, pinstriped suit in the store.
The salesman will eventually realize that you're serious about your budget, and will kindly help you find a suit that is within your price range.
Finally, leave home happy with this awesome piece of clothing.