I'd say getting it all done for less than $50 will be difficult. Some smiths charge $25 or even $50 per hole for D&T, usually more for dovetails, so you just aren't going to get there. To make it look right, you might need to look into cutting a custom base for your desired sight in order to get the right height (that's what I would do). Williams and Marbles both have adjustable height sights, or sight bases/risers, so I'd take a look through their catalogs. NECG (among others) sell component bases to be used as starting points for scratch builds. With enough elbow grease and a steady hand, anyone with a drill press, time/patience, and a bit of know how can cut their own base and install sights themselves.

You can likely get the parts all for less than $50, but you'll have to do the dovetailing or D&T yourself, otherwise gunsmith fees are going to go over $50.