You can get a complete, ready to use VV box mod at MV for 34.99. You can add a charger and a couple of 14500 batteries and still be around your $50.00 price tag. I bought and built the kit version last February and it is still going strong. I have used mine for months as my primary pv.
I just picked up a VV Gripper from MV, they are on sale now for about $40.00. This is probably not going to be the most durable mod, problems with battery door as the leading source of failure, but if, when my Gripper breaks, I'll put the guts in another box. Adding new batteries and a charger will likely exceed your price guideline. My first Gripper was DOA, but had no problems getting a replacement from MV in less than week. I've only been using my Gripper for two days now, but overall I like it.
Look around, other places/sites have other options; Discount Vapers has some lower-priced VV mods.
Hope this helps and good luck.