Finstar :
R7 260, HD 7770, GTX 560 TI.
Just to say beware of HD7770 from china.
GTX 560Ti is better recommended.
And also to add HD5870 is same HD5850 but with slightly higher clocks, which you can manually overclock.
Is the budget strictly under 30$? And also it really depends where do you live since shipping.
Also check for auciton.