Her2 Serum Test

I just read Christine's birthday news post and am interested in info about the her2 serum test.
My onc does not do routine scans or tumor markers. I'll be finishing with herceptin in 12/06 (hopefully), my muga last week was at 50% down 6%.
Was dx at age 46 (premeno) stage 1 with 1.5cm and .4cm masses, er-pr-, her 2+++.
Had lumpectomy along with 4 cycles of A/C, taxol with herceptin, then 26 rads, continue with herceptin to equal 1 year.
Am taking COQ10, multivitamin, calcium as supplements.
Very fearful to recurrance and proceeding to stage 4. There appears to be many people moving from stage 1 to stage 4. Would like to do everything in my power to avoid mets and if mets are inevilable then want them caught early.
How do I get the test? Is it expensive and that is why my onc hasn't mentioned it? I have insurance that has been paying for my treatment so far without problems.
Also has anyone maxed out their insurance? Is this another worry I should be thinking about?
Thanks for your help.
Rocky