A couple of thoughts:
* Get indicative prices for each of those products before you spend too much time evaluating them. No point spending a lot of time & effort on evaluating them, then realising that the one you want is way above your budget.
* At your size network, it doesn't really matter that much what you choose. Most products will do a reasonable job. So don't waste a lot of time & energy on detailed comparisons.
* If you're going to use HP wireless, then you'll probably end up needing to use IMC. So you might as well start with IMC, and see if it meets your needs/budget. If it does, then just go with that.
Look at the rest of your monitoring needs - do you need to integrate with other monitoring systems (applications, servers, etc) ? Or does your network team operate in isolation? That affects some of your choices.