For HDRs you don't need anything special, just any tripod that can sustain the weight of your camera will do. So select by price, weight, robustness (choose any two). If you want to take panoramas too, consider buying a tripod with interchangeable heads.

Regarding the head. I find ball heads easier to use in most situations, you can compose quicker. But ball heads are less precise, and they are definitely not good for panoramas, because it's difficult to rotate around the same axis.

For panoramas you can use the same tripod, but you better use a two- or three-axis head or any head + rotator. And if you have more money to spend, the best you can do is to by a specialized panoramic head (e.g. one of the Nodal Ninja heads). They allow to adjust your camera's position in such a way, that the rotation axis passes through the pivot point.

See this article to learn about the pivot point: The proper pivot point for panoramic photography [PDF].

Definitely, panoramic heads are beyond your current budget ($75), but there are some decent tripods with interchangeable heads (see, for example, this question). So you may buy a good tripod now, and buy a panoramic head later if you really want it (Or maybe you'll be satisfied with the standard head). Or you may save more and buy a lightweight tripod with a non-interchangeable head. In this case prefer three-axis heads if you are going to shoot panoramas. I used such a tripod (≈ $30) with a compact camera, it was usable but not perfect.