In 9mm if you're only going to buy new my list would be in order of preference:
CZ
SigSauer
Glock
Springfield
If you're going to consider used 9mm's then I would rank as follows:
SigSauer
CZ
Glock
Beretta
CZ's are a GREAT value for the money. I've had three roll through my safe over the years. While all are no longer there, the reason is that I got trade offers on them that were equal to or exceeded what I paid for them. They're accurate, reliable (the only one I ever had choke was on CCI aluminum case ammo), they point great and the triggers break in well. Also I REALLY enjoyed the fact that you could get a bunch of different mags for them as there are lots of CZ knock offs. This made finding high caps easy during the dark days of the Klinton Ban, but now you can get new high caps for just over $25.
Also check around as CZ was blowing out CZ85's a while back that had them at the local shop for $369 for a CZ85B with 2 16rd mags and all the CZ extras which is a downright awesome deal.
After the CZ I'd look for a used SigSauer. One store by me has used 226's for $399 at the moment and I picked up a used 229 with 5 13rd mags for $467 a few weeks back. Sigs are excellent firearms and you can't go wrong with them. The only reason I'd put a CZ over a sig is that the new prices on CZ's are much lower than sigs and sometimes the used sig market can vary widely. If you're friend is just looking for a plinker 9mm then getting the best possible firearm for the lowest price is probably his motivating factor and I think the CZ edges the Sig out in that department until you hit the used market.
Again, thats my two cents, take it for what you want, but with a CZ or Sig your friend won't go wrong. They're both excellent firearms that will provide YEARS of service. Let us know what he gets...