hmm its actually up to you (ts)...
if you are really into photography, why not top up abit more? for newer model? like 3100 or 5100 and it might last you
longer? hmm. you can get a 2nd 3100 in BnS for like less 650? +/- with kit lens (18-55) or if you want 18-105, u can
sell your 18-55 and top up (maybe $130+/-) for a 18-105?
if im not wrong d40 is actually quite an old model.
well in the end its still up to you =D..