Buy one with red LED's. It's much more efficient. Red LED's only produce red light, so all of the energy goes to producing light. If you put a red lens in front of a white light, it filters out everything but the red portion of the white light. All of the energy used to produce the non-red portion is wasted. This is particularly problematic with white LED's, which produce relatively little red light -- their light is noticeably bluer and whiter than incandescant.

Here's a link to a red LED MR16 for less than $8: http://store.peclamp.com/led001.html