Have a good hunt around eBay, and check in the US too, you can pick up some good prices, the only downside form the US is the postage time. My order took a week for the funds to clear and 2 weeks for the shipping time, but I got a great 5751 Tung-Sol NOS quad for under 40 quid inc postage! (pound to dollar rate is very favourable at the moment, well favourable to UK buyers anyway).