Sourcing Ingredients for Root Beer

I'm planning on making a batch of root beer and am trying to source my ingredients. I would like to make a non-kit, non-extract batch, so I'm looking for sarsaparilla root, sassafras root, burdock root, etc. I stopped in my LHBS and they had a few things but didn't carry the different roots. Ideally I'd like to just visit a local store but ordering online is of course an option as well. Does anyone know any stores that carry these types of ingredients in the Midwest? Chicago area or Indianapolis area are preferred as I'll be travelling between the two this weekend. Or where have you purchased these ingredients online? I did find one company, Monterey Bay Spice Co. (California) but after putting the ingredients together shipping ends up being half of the order so I thought it might be worth to shop around a bit.

Also, a few other questions regarding root beer. When looking for sarsaparilla I have seen Mexican, Jamaican, and Indian varieties. Can anyone weigh in on the difference each of these may make in your root beer?

The recipes that I have found are specifying the roots in volume (tbs typically) but the sites I have found that sell the different roots specify them by weight, typically 1/4lb increments. Does anyone have any sort of conversation as to, say, how many tablespoons of sarsaparilla you'll get out of 1/4 lb?

edit:
I'm going to put down a few I've spotted during my search and suggestions from below.

Local specialty spices & herb shop
Local homebrew shop
www.mountainroseherbs.com
www.herbco.com
www.amazon.com

I got a lot of my ingredients on Amazon.com. I was able to find sarsaparilla, star anise and cinnamon sticks at my LHBS. I looked everywhere locally for the sassafras, but it was hopeless. You may have luck at a specialty tea/herb store?

Sassafras is also my biggest problem so far. Monterey Bay Spice Co does have sassafras root bark but you can only get it in increments of 1/4 lbs. Then it is $14 per 1/4 lb (or $35 for 1 lb) plus to get it to me shipping is almost $8 just for sassafras. Maybe it is a better deal when you order more at a time but I'll have to look around for some specialty herb stores like you suggested.

From the reading on sarsaparilla that I have done over the years, Jamaican is the preferred one with Honduran or Mexican following.
With sassafrass you ideally want the root bark, but the whole root works too. Depending on where you live in US you may have a plethora of trees in your area. Fresh root bark is awesome, and believe it or not there are several vendors on eBay who send the entire root freshly dug and typically will cut to your requested proportion. You can also find reputable spice vendors on eBay. Another company I like is morethanalive.com, they may offer what you are seeking, along with Atlantic Spice Company.

You could try your local farm co-ops. Long shot but it's worth a google search and couple of phone calls.