If your insurance won't cover it, you could spend more on the exam and inserts than your boots! From my insurance company:
Podiatrist exam "Evaluation and management of an established patient in an office or outpatient location for 25 minutes."
Billed: $251.00 (the charge if I didn't have insurance?)
Allowed: $112.69 (what Medicare allows to be charged?)
Facility charge: "Hospital outpatient clinic visit for assessment and management of a patient
Billed: $354.89
Allowed: $133.47
(But it's cheaper to go to a physician's office than to a hospital clinic.)
Diabetic inserts: "FOR DIABETICS ONLY, MULTIPLE DENSITY INSERT, MADE BY DIRECT CARVING WITH CAM TECHNOLOGY FROM A RECTIFIED CAD MODEL CREATED FROM A DIGITIZED SCAN OF THE PATIENT, TOTAL CONTACT WITH PATIENT'S FOOT, INCLUDING ARCH, BASE LAYER MINIMUM OF 3/16 INCH MATERIAL OF SHORE A 35 DUROMETER (OR HIGHER), INCLUDES ARCH FILLER AND OTHER SHAPING MATERIAL, CUSTOM FABRICATED, EACH"
Billed: $687 / foot (They gave me 3 inserts / foot)
Allowed: $84.33 / foot
(Non-diabetic inserts might be cheaper.)
Incidentally my shoes look like very good quality somewhat high cross training shoes: "For diabetics only, fitting (including follow-up), custom preparation and supply of off-the-shelf depth-inlay shoe manufactured to accommodate multi-density insert(s)"
Billed: $139 / shoe
Allowed: $46.17 / shoe
(I assume orthotic grade skate boots, if available, are much more expensive.)