Dean,
It also depends how much meat you need to smoke and what type of meat you want to smoke.
I only know about the Lang line of smokers.
The 36" is not set up as a trailerable smoker but can be modified by you or Lang. It runs $1395 for the original and $1695 for the hybrid (which is what I have. It cooks (4) 10# butts and (2) 16# briskets at the same time or (1) 36# whole hog.
The 48" is designed as a trailerable unit. It runs ~$2495. Smokes (10) 8# butts or (20) 1/2 chickens or (1) 70# whole hog.
The 60" is trailerable and runs ~$3195. Smokes 40-45 1/2 chickens or (20) 8# butts or (15) slabs of ribs or (1) 100# hog.
The units have an original version and then a hybrid version that has a warming box. It's great for side dishes but can also be controlled to stay as hot as the smoker side which allows for even more food to be on the grill.
If you only smoke chicken pieces on the units above, you could smoke an entire chicken coup full of meat! If you get a unit that is large enough you will eventually succumb to wanting to smoke a whole hog. I know because that's what I'm doing next weekend now that I have a unit large enough.
Here's Lang's website:
http://langbbqsmokers.com/index.html
I think I remember seeing a Lang for sale on the forum the other day. I believe it's a 60". Just check out the for sale items forum.
Hope this helps. Let us know what you decide.
WC
EDIT: The unit I saw for sale is a Lang 36" for $850 and is located in Jackson, MS.
Here's the link:
http://www.smokingmeatforums.com/t/123990/marcus-b-walker
WC