This is will depend heavily on the amount of users you will have, but let's say you go for 250 users with 100 live channels (I prefer having live channels since with that it will prevent some common problems with on-demand, more on this search the forum)
I would go with a MAIN server that can support a lot of requests, so something with very good RAM (the more you put into it now the better, it will save you a lot of work changing main server latter on), after that maybe a 1Gbps server for LB.
I normally recommend starting with No quote servers, they're cheap and reliable since they use No quote & others well know data centers.
The most important thing is finding a good reliable channels provider, don't go cheap with this, and don't go with restream lines (more on this search the forum), search for someone with local channels on the main use country that you will be selling.
So, price?
No quote
I have to say that probably you could start with less connections and them build up on that if you need it so, but don't do cheap on this, if you need go with maybe 20 connections or so, that way you would save some money, and when you build your user database increase that.
Nevertheless this is ONLY my option and take on this, hope it helps.