I still have my Manuarm, my first ever airgun and to be fair it has taken in its stride all the abuse a fourteen year old boy with a penchant for experimental ballistics could dish out!
Not bad for £20. I think a Gat in the basic box without all the corks and darts was about £8 at the same shop.

Anyone know the dimensions of the standard mainspring might be, and what other gun's springs might be equivalent? Mine got replaced by the gunsmith after the original broke but he used a thinner wire spring as he couldn't get a proper spare.