Hello and welcome to just answer Dodge. I have heard this before and it has always been a lifter problem. You will need to remove the right valve cover to determine which one it is. The cylinder head will need to be removed to do this. As far as cost, parts will not be too much (gaskets and the lifter itself) probably around $200.00. But labor will be about 5 hours or so. So based on a rate of $100.00, labor will be around $500.00. So the total should be around $750.00.
Hope this information helps, and let me know if you need more assistance with this.