Best price I've seen lately for the hvac module is $118,
here. Think I paid $110 for mine.
I would check car-part.com for the radio. This is where I found mine. It's a database of scrap yards. Got my 15 RA4 for $545. Not the best price I've seen, but also not the worst and a lot cheaper than Ebay. There are some RA3s on there for as low as $195. Just look at the part rating. If it's not an "A" I wouldn't buy it. And don't necessarily go by the pictures they have. A lot of them show dirt/mud on the interior, but most of the time if it's an "A" rating, it's in better shape than what the pic shows (if the pic is of it still in the vehicle). And most of the yards have a warranty period, so you can send the part back if you get it and something is wrong. Also, the site will pull up radios from non-RAM vehicles, but what you need to look at is the part number for the radio. If you put the part number into
this site, it will tell you whether the radio is a RA3 or RA4. Lastly, I would always email the yard and ask for pictures of the front and back of the radio. This allows you to verify the condition and the part number of the radio.
Additionally, the radiocode website allows you to buy the security code for the radio for $10. You will need the code to activate the radio once it's installed in your truck. Some people have had luck getting this from the dealer, but I didn't even attempt going through mine just based on past experience with them adding sales codes for my backup camera.