There are (2) units that I would suggest in your price range that would deliver the best bang for the buck.
The Digital Ranger is our #1 selling unit it retails for 399.99. We sell a ton of these to patrol units all over the us becuase of its features.
1) Day and Night Usable
2) Video Output Capability
3) Resolution simmilar to Gen 2 (Effective range of 200+ yards)
As for a unit that retails around $100 I would recomend the Yukon
Spirit 2X, NVMT 2X, and Nightfall 3X.....These untis range from $150-$199 and will get the job done for anything under 100 yards. All of these units come with a lifetime warranty.