If there's one thing I really like - it's saving money. Take grippers for instance, now I aint never gonna be mega-strong gripwise; but I do understand the need to train the grip. Enter the Ivanko Super Gripper (Pullum-Sports UK).

Usually supplied with two springs - providing around 50 levels of resistance (45-360lbs), some like those supplied by Hammar Sports come with an extra spring taking the max to approx. 470lbs (and custom knurled grips) Iron Woody also do the custom grip thing.

Here's the data sheet for two springs: (calc for more springs)