Tbh I occasionaly send out these sort of emails to sites. I dont see it as spamming and whilst generally the response rate is low its not not significantly lower than much more personalised emails which take a lot of time to write and are probably not worth it.
However, I also personally contact more relevant sites to negotiate custom exchanges.
Get yourself some proper code that checks for reciprocal links. My coder knocked up something in a very short space of time and it makes monitoring a breeze.