1x ~late 80s alphanumeric: ES/WW/Taxi/etc. (<$2k)
1x ~"affordable" 90s DMD: NGG/HS2/T2/etc. (<$3.5k)
1x newer Stern: LOTR/POTC/BDK/ACDC Pro/etc. (<$4.5k)
Obviously you would be limiting or expanding choice in each bucket based on how much you spent in other buckets...E.g.: Could maybe get CFTBL/TAF/CP in bucket 2 if you got a good deal on a Taxi...Or could maybe snag an AC/DC Premium or equivalent if you get a good deal on a T2 or HS2.
...Try to have at least one "deep" game and one that's easy to pick up...Second on having one that appeals to the significant other and none that makes him/her want to throw up.