Just read your need for 4 hours of DAT quality and new DAT deck prices. You
should be using 4 hour data DAT tapes.
I've been using data DAT tapes for the very purpose you need them (opera from
radio). They're no different in quality for domestic purposes to audio DAT
tapes and about half the price. You should be using data DAT anyway to keep the
costs down.

As for new decks, a perfectly suitable machine for timer operated recordings at
home is the Tascam DA20 which can be had for half the price you've suggested:
http://www.turnkey.uk.com/tkweb/stoc...20&context=WEB.
BTW, Turnkey are far from being the cheapest, so look around...

Mike