Those guns you showed suck ass. If you actually want to airsoft, I suggest you save up your money for a bit and buy an actual sniper rifle with an actual scope, or buy an all-plastic piece of stuff crap internals gun that shoots 15 feet as said above.
There is no point in saying "Oh I have 30, I'm going to buy a cheap airsoft sniper rifle"
AT LEAST gather 20-40 more.
Also, shop airsoftgi. They have plenty of sniper rifles in the "Under $100" range.
http://www.airsoftgi.com/shop_by_price.php?range=0&sort=5a&PLsort=5a&page=3kthx. But it shoots 250-300 FPS.
That's stuff
and I know you are not going all out, but get something decent you can actually use and not a $10-20 scope either.