Timing chain replacement is actually a lot easier (labour wise) than changing a timing belt of the older Honda engines. Furthermore, the parts involved is not just the timing chain itself, here's the MSRP of parts you should replace if you have a stretched chain (total $320ish):
008 14401-PPA-004 CHAIN (176L) (BORG WARNER) 001 2005 TSX 106.80
009 14510-PRB-A01 TENSIONER ASSY., CAM CHAIN 001 2005 TSX 78.40
011 14520-RAA-A01 ARM, CAM CHAIN TENSIONER 001 2005 TSX 98.08
012 14530-RZA-A01 GUIDE, CAM CHAIN 001 2005 TSX 21.40
013 14540-PRB-A01 GUIDE B, CAM CHAIN 001 2005 TSX 17.05