I'm thinking of getting a new one (12v) but noticed prices vary wildly.
I expect you get what you pay, but its only for occasional use, so I don't want to shell out too much.
Whats my best bet and are amps important ?
If I were buying one, I'd seriously consider this one. Quite sophisticated at a bargain price and 3-year warranty (available from Thursday 15th): http://www.lidl.co.uk/en/our-offers-2491.htm?action=showDetail&id=20000&ar=2
I'd second that one and it's a good price. The more expensive ones are higher current but more bulky, have more gimmicks or are more robust, none of these things matter to most users so stick with simple !