Hello,
 I've tried out faceware with the built in webcam ( which is completely pixelated and dark over all (2-5mb) ) with a good lighting I was able to get a pretty decent results and over FPS counter (of faceware) it read 30FPS.

the purchase of a new cam or action cam is on my mind, but I'm not sure if I really need something as big as c90, I mean it's much wider and it could get 60 and maybe even 90FPS, but do we really need that much fps?

Other good and cheaper alternatives like  (c270 , c310, c525e ..) they have a decent quality and they never lag (constant 30 FPS ) based on most of the youtube review, however, they have a bit narrower angle, less magapixels ( 5 & 8 .. while c920 is 15 ) , and they don't seem to have "autofocus".

I still can't make my mind, am I sacrificing anything buy not investing in something as big as c920?

if you have experienced with any more budget webcams please let me know

Thanks.