Pretty much the only mains ones I'd suggest are the Maestri ME 606 18 ga brad gun/stapler, or the ME30-08 for the 21 ga veneer pinner - neither of which come in at anywhere near your £120 budget, I'm afraid. If it's just for workshop use and if you have a compressor, then an air gun might be a better option??
Is there a particular reason for wanting electric? I only ask because I wanted a nail gun recently, and was going to get an electric one because I thought it would be cheaper than a compressor & nailer. Turns out it wasn't really - I end up getting a Makita 18 gauge and a compressor for about £140, and I have the versatility of getting other attachments for the compressor if I want
FWIW electric pin guns / staplers are generally quite a bit smaller than air powered models, and a cable is more flexible than a hose; personally, I just find them generally easier to handle, and you can use them more easily out of the workshop, of course. Not a knock against a compressor, or cheap air tools - I wouldn't want to be without mine - but I do like my electric nailers...
