Do you have good to great binos that you can mount to a good tripod? If no, I would put the money into getting to that point first. Many people think they need more magnification when what most of us really need is more resolution. A smaller sharper image is better than a larger blurrier one. Even if a mid range spotter can show a bit more detail than a high-end pair of binoculars, the great binos will be helpful 100% of the time that you're glassing instead of the 10 to 20% that most people use a spotting scope for.
A pair of SLC, Kowa BD, Nikon HG, Maven B series, Leica Trinovid, etc on a good tripod are amazingly good. If you're hand holding a pair of Vipers or Leupold binos, that setup will blow your mind. Bino upgrade is also much lighter in the pack than adding a spotter.
If you have a top shelf pair of binoculars and a good tripod already, then the spotter could be worth it. I would do everything I could to stretch the budget a little bit and look at a used leica 62, or Kowa 663/664. If the budget is the budget, a Nikon ED50 or the Athlon Ares 65 are fantastic compact spotters for the money. A used Kowa 662 would be a good option as well. I would for sure recommend 30x fixed eyepiece for it instead of a zoom. Having looked through most of these side-by-side by side against various Swaro, Maven, Vortex, Leupold, etc it's what I would pick for myself.