A simple and cheap solution is to get one of those collapsible stainless steel steamer inserts. It'll fit in many different saucepans. They work fine. The quality of the saucepan isn't critical, since all you're using the pot for is to boil about an inch of water under the steamer insert. The main thing is having a snug lid on the saucepan.

Most sets of cookware these days have a steamer insert which will fit one of the medium size saucepans.

If you're acquiring pots & pans right now, consider this: I have a three piece (four, if you count the lid) stainless set stockpot set from Tramontina I got at Sam's. Moderately large stockpot, a pasta insert and a steamer insert. Reasonably priced (I think it was around $30 or so), heavy duty. The steamer portion is big enough to hold a 4 lb chicken, so you can steam almost anything.

With that one purchase you have the tools to steam all the veggies and shrimp you want, and also can use it for cooking rice or pasta. (see in the thread below my post on using a steamer insert to cook rice)

Here is a link that might be useful: cooking rice