I would suggest you these:
http://www.bonlook.com/product/jadore-tortoise-sun
They are not Serengeti but BonLook. You'll get the SAME QUALITY without spending a fortune.
The frames are crafted out of italian acetate and have spring hinges. You can add Rx if you wish and the lenses all have high quality anti-reflective, scratch-resistant and UV protections and are customized in an optical laboratory in the US that serves hundreds of optical stores.
Green Shipping is also included you will receive your glasses in 2-5 days.
If you're not satisfied, BonLook accepts returns and refunds.
All this for $119, Rx included.