The majority opinion of the "best" tapes to get suggests U-571 and X-Men, as far as pic and audio. I have X-Men, which is excellent, but I can't comment on U-571. I bought T2 (just to say I have it on every blasted format on the planet), but it's not the best. Better than the Ultimate dvd, but...
bestprices.com is probably the lowest priced retailer you'll find. I have ordered from them in the past many times. From what I've gathered, stick to ordering what they list as in-stock. Also there's dvdempire.com whose prices are a little higher than bestprices. If you have a Tower Records...