In my SOB trailer I used a Samsung "Home Theater in a Box". It came with speakers, that I didn't use, but it was a direct replacement for the all in one DVD player. It has a 5.1 receiver and blu ray player. I think I paid $250-$300 at Best Buy last summer. I will be taking it out and putting it in the new trailer as soon as it gets here.
Searching Amazon and the like for "home theater in a box" will get you pointed in the right direction. I wouldn't bother trying to find one without speakers. They all come with them now. It was still cheaper by about a $100 to buy this than a stand alone blu ray and 5.1 reciever, even with the speakers I won't use.
Here's a
link to what I bought.