If you're willing to add another $25 (approximately)to your vv mod budget check out the new Buzz, looks sweet and the VV adjustment is a dial right on top looks like... pretty cool, and it takes 2 18350's I believe.
Also, There's the Indulgence. it's not VV per se, but the stock unit uses an 18350. You can get the extended sleeve for about $20 so you can stack batts for 6v, 7.4v, or the new 4.8v batt they have at madvapes. That would fall into your $75 budget, minus batteries of course.... with many voltage options. I have one and I like it.