muffstah you have pm.
To clarify my point a bit.
You can return the HD as a procedural return. There are two ways to do this.
#1-Return at 99, rebuy at 99, get rebate. (register total=0, neglecting any difference in %110 PMs.) Can be difficult because their price discrepencies will show a large hit. Gets LP guys antsy.
#2-Somewhat more confusing. Bring in an empty box. Say you want to get a rebate on an item you bought last week. They will do a procedural return. Basically return without receipt (they ask for your info, etc...then they will manually input 179), then re-ring up product at 199-20 instant, hit total, register defaults to cash, receipt prints with rebate form. (179-179=0)