2000 Ram Van 3.9L bubbles in radiator

My van has bubbles in the radiator that comes and goes and sometimes overheats.
I changed and flushed my system and filled with new coolant.
I could drive it for about 10 miles and everythings okay.
It does not have any water in my oil or oil in my coolant.
It doesn't blow any white smoke out of the tail pipe either.
I also changed the thermostat and even took the thermostat out of the housing and I am running it that way.The temp stays about 130 deg. until it gets hot.
I have a suspicion it is a head gasket.
I even changed the radiator cap. the only things I haven't changed is the hoses. It has 150k on it.
Does anyone know what it will probably cost the repair the head gasket???
Thanks,
Ricky Newman

I have a suspicion it is a head gasket.

I agree. Try calling around to some local mechanics for a price.
I would suggest to do both heads, even though, chances are, just one is leaking.
Also, often there is a reason for a gasket to blow, consider telling the mechanic to send out both heads to a machine shop for pressure testing, warp testing, check for cracks etc.

Alternately, if you feel very, very lucky, try re-torquing all the head bolts first. It's a long shot, but it might stop the leak, at least temporarily

Ditto on the head gasket. There's a couple of places on eBay that sell the heads for about $150 each and you send your old ones back to them. With a 2000 I would assume your mileage is up around 100K or so. Because of that, if you buy a set of heads and swap them out, you'll end up with a valve job in the process. You'll also know that you have a set of straight heads with no cracks in them either. The other plus is that you can do all the swapping on a Saturday and reduce the down time for your van.