HHA (Sports Optimizer Lite) if you want to give one a shot for < $100 (i got mine at $93 on amazon). I dialed in the sight-tape and was extremely accurate when adjusting the yardage up to 80 yards (70 lb draw). That said... it was only practical for the archery range.
I went back to multi-pin (20, 30, 40, 50, 55, 60) due to the tight-profile and feels lighter as the sight pushed my quiver out farther which messed with weight and balance.
If you end up liking a single-pin adjustable, my guys say the best is the Spot Hog Fast Eddie (~$330). I can confirm, the boys shoot pretty well past 80 yards...
(If you're interested in mine, hmu and we can talk $).