Used pre amp advice

Any opinions on the best "bang for your buck" preamp/with phono section-for under 500.00. Thanks in advance.
used threshold
Anything with a brand name you recognize that is tubed.
That is super tough. Anything with a good phone even 10 years old will be a lot more. You may be unrealistic but also consider an older and nicer pre-amp without phono and strap on a used Parasound PH-100 phono stage which you can find for around $80. If you are willing to do that, the best pre-amp for the money I know of in your price range is the Musical Design tube pre-amp designed by John Hillig in St. Louis. try to get an SP-2 over an SP-1. You will also like an older VSP Labs, Acoustat, or New York Audio Labs.
audible illusions...
McIntosh C712 - I have compared it to several preamps in this price range and the Mc is killer. Used prices have been on the increase in the last year though...
forgot to mention the arc sp9 ( goes for a little more but very reliable and serviceable if needed).
I love my Classe 30 with phono. B&K's are nice also.
If you buy an older tube amp I strongly urge you to have it inspected by a qualified technician as part of the deal. Many of these older units have capacitors, and tubes often, that require replacement. It can be disastrous to use one with such capacitors; it may sound OK for some time and then fail.

Assume you will spend some money to bring a used tube (if older) up to date when you budget for your purchase. The only exception to this would be if the unit has been serviced recently and it is documented. It is also good to find out if the unit can still be serviced. Sometimes they use parts that no longe exist and cannot be found anywhere; I have such an anchor that I (foolishly and had not yet learned my lesson) have under a couch waiting for the parts to pop up used; they are no longer made. That was a year ago and it still sits under the couch.