I'm considering bidding on ebay for several amps: peavey 5150, mesa DC, and mesa F50. which of these are best for playing death metal and blues? (cleans would be nice, but not an absolute necessity)
If you can find one, I'd go with the Mesa DC-5. Very underrated amp by Mesa, much better than the F-50. The DC-5 has very nice cleans, can do blues, and will even pump out some serious metal tones.
DC10 for under $500. should i jump on it?

also some cheap mark 2s and 3s. ARGH TOO MANY TO CHOOSE FROM. halp?
Is that the combo or the head? How much is the Mark II and Mark III going for? Where'd you find them at?
all combos, all ebay. by cheap i mean under $700, but they could easily have high reserves?

i'm just really not sure on the sound of the DC because i haven't found many sound clips of it. i know the 5150 is what in flames uses (i think their tone post-whoracle is great) and dream theater uses mark 2 amps, but the other marks and the DC are total for me.
$500 for a DC-10 is a good deal. $700 is pushing it though, I wouldn't go that high. The 5150 is a great amp for metal, but it's not going to do blues very well and the cleans are dull. Petrucci has used the Mark IIC+ in the past, but hasn't used any of the DC amps, at least not on any albums. The DC amps can get you a Recto tone. I'd take a DC over a Recto any day. The cleans really stand out and the lead channel easily sounds better than a Recto. They are very loud and have more than enough gain.
I don't think there's a Mark II combo, at least I've never seen or heard about one. There are four different Mark II's - IIA, IIB, IIC, and IIC+ If the price is right, you can't go wrong with any of the Mark Series amps.