I'd say, in order of importance on how to spread your money:
- Speakers, including subwoofer - at least 50% of your expenditure (I did about 70%).
- Room treatments. To tame your room.
- Receiver - pick for features, most current receivers will handle the power requirements correctly.
- Any media sources - pick by type of media you want to use, features and what you want to spend. Now this is a bluray player or a streaming box, but a lot of streaming is done by TV's.
- cables and connectors. These should be the least of your expense.
Many people don't use room treatments, but these can have great impact on the sound. You should spend a higher amount on your bluray player only if you want the features that a higher priced player delivers. Otherwise, get a good reliable mid or lower range player.