Your going to run into a few challenges by limiting yourself to that amount of cash.
First the size will be limited so if you want to cut larger designs, 16 inches is a lot smaller then 20. If you plan on doing simple smaller inlays and have no desire to expand your repertoire... then maybe a 16 inch will do. When talking measurements in scroll saws, we are talking about the distance between the blade and arm (body) of saw.
Weight is another issue with scroll saws. The less expensive ones will tend to vibrate and make your work difficult to accomplish. You can bolt the saw down on a bench, table or stand, but many of these saws are not well designed and the table may sill vibrate a bit.
Do stay away from the older models that only take the pin type of blades. These are wider and can not do intricate work. Also get a saw that has an arm you lift up. Older saws have stable arms so when you want to move from one design feature to the next, you have to release the blade from the bottom, remove it, position your work, and drop the blade down through the next pre-driled hole. Securing the blade under the table gets old real fast.
Some older saws are better built then some of the new ones so that might be in your favor. An example is the Dewalt saws. They went from NA built to overseas built and they have lost some of their quality. That is the opinion of folks who have posted on the topic. I got lucky and bought mine when they still being built here and in Canada.
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