Where can I get the best deal on SIPs? I am located in the upper peninsula of michigan. Thanks!

What type of SIPs do you want?  OSB or metal skin - EPS or polyurethane cores?

I was thinking about osb but do they make treated ones for below grade? As far as the EPS or polystyrene whichever has the best R Value.

I would be very hesitant using a wood product such as OSB below grade.  I have see metal skin SIPs installed below grade but I did not encourage it.  I would have more confidence in reinforced concrete below grade for strength and water tightness.  The reinforced concrete could be formed many different ways including ICF.

EPS is expanded polystyrene.  XPS is extruded polystyrene such as Styrofoam.  SIPs with closed cell polyurethane cores have a higher R-value per inch than EPS (polystyrene) but cost more.

If your site can tolerate thick walls, then consider EPS cores for the roof and walls above grade.  Compare prices for the same R-value and less thickness of polyurethane filled SIPs.

In termite infested areas, I prefer metal skin SIPs.  No worry about termites eating away the structure of the wall.

enercept builds basement sip panels with treated plywood

Posted By slowroadster on 20 Apr 2013 12:57 PM
enercept builds basement sip panels with treated plywood

Though pressure treated wood may discourage termite infestation, it does not prohibit it.
Termites will attack pressure treated wood through the ends, any cracks and fissures, and will also build tunnels on top of it.
Pressure treated wood is poisonous to insects bacteria, and fungi so it will discourage new colonies from forming,
but keep in mind that like anything else pressure treated wood will deteriorate over time and exposure to the elements leaving it susceptible to the same assailants as any other lumber.