I've had a couple of older 3-9x40mm Tasco Pronhorns (80's manufacture, 80's price was around $279) that have lasted decades on a .338 win mag and a .270. Nothing wrong with that generation of Tasco's, period.
The new Target/Varmint ones are not as tough, but they're selling for $90 - $110 in 2014 dollars, so what do you expect?
Tasco still warranties them immediately (I just got a new 6-24x42 sent to me, no questions asked, after my M-14 rattled one up pretty bad.), and lots of guys get lots of mileage out of them. I've had three on rifles for a few years and only the one on the M-14 had an issue, and M-14's are known to be rough on scopes.
You still need to be aware that a $100 Tasco isn't a $350 VX-2, but I'm okay going afield with my 6.5 x 55 wearing a $100 Tasco.