(Let me preface this with saying I'm interested in physical equipment. I'm not really interested in running GNS3 at this time. I have a fairly robust hardware lab already)
I would like something for CCNA:Sec to last through CCNP:Security. After reading the 
Exam Objectives and looking at the 
ASA Compatibility Site, am I correct in concluding that I could purchase some 5510 ASAs with 
IPS modules and be good to go as far as exam topics go?
The exam topics state:
- 5.3 Implement NAT on Cisco ASA 9.x
 
- Firewall features on the Cisco Adaptive Security Appliance (ASA) 9.x
 
The compatibility site says the 5510 supports up to ASA OS 9.1(6).
Is there anything I'm missing here?  Any tips on purchasing used ASAs?
Thanks for reading