<<<I don't want to spend a fortune>>>
Most people mean over $200 then they say that. Most reliable diversity radio microphones start about $800 to $1000. The new Sennheiser seems to have broken that barrier. It also seems to be the only one.
Don't bother spending less. What you lose in production time and aggravation with a cheap radio mic will more than pay for a new, better one.
There are also a number of production shooters that will still open a vein before using a raldio mic--having been burned a number of times by RF's unreliability. So if you're dong this as a convenience instead of raw necessity, I would reconsider.
What's it worth to you to blow 5% to 10% of your shoots--at random.
Koz