Because this forum is actually sponsored by Community123.com who are in the business of HOA websites, most folks here are a little more discreet about posting their competitors .. .. ..
In fact, it wouldn't surprise me if this thread disappears
While our HOA doesn't use Community123.com, I've heard nothing but good things about them and they certainly are reasonably priced for what they provide, customized and all.
Our community does use a competitor that doesn't base the monthly fees on the number of members, but rather on the level of website functionality.
We have 3+ years experience with this vendor and are extremely pleased.
I suggest that your best strategy is to realistically determine how many of the three broad types of functionality that a website can provide you'll actually use:
1). Community Communication (largely 1 way from HOA to owners)
2). Interactive Communication (2 way between HOA and owners)
3). HOA Management Functions
The more you want, the more it will cost you, but be realistic in your approach.