The cheapy UV lights have LEDs in the range of 395-410nm which are barely decent in finding/seeing pet stains.
I would recommend the Arc UV AAA which has UV in the range of 375nm and does a great job at lighting up pet stains.
I've been through a handful of cheapy UV lights and also had an Inova UV, but the Arc is by far the best at fluorescing up things.
The Arc UV is however $40 + shipping but worth it IMO. Its built to last a lifetime, extremely small/compact, and the best UV glowing ability I've encountered.