Hello EMC community

I have an CX-2 DAE which I am trying to pair up with a cheap SPE. I have asked around and a person was kind enough to offer a compatibility list, what I am looking for is to see what the lowest-cost option would be. I know I need a SPE with vault drives to get it all running but all I have been able to find so far on ebay is upwards of $2500 even for the oldest systems. Does this sound about right or is there some option I am not aware of? I bought the DAE for around $300 so I was hoping that the rest of the system would cost around $500.

This is my first build and it is for a home lab. Basically, if you were me, what would you do? If it costs $2500-3000 to get the lab going, so be it. It will just take longer to pull the money together than I originally intended.