Dealextreme are currently selling this tablet at less than $42 (I'm in the UK and this works out less than £25). I've ordered from them before - they're based in China so items can take a bit longer to arrive but they're a big company and very reliable (in case you are at all concerned about ordering from China, you can pay by Paypal so it's backed up by Paypal's guarantee anyway).

Obviously this isn't the highest spec tablet every but for the money it's excellent and the spec is perfectly reasonable. It runs Android 4.1 and has a 1Ghz processor, with a 7" screen and 512Mb of RAM. Also comes with a case and keyboard!

This has got to be worth a punt for the price!