Starting Friday, you can buy instead of rent during RentTheRunway.com’s first sale. Retired merchandise from the designer rental boutique will be priced at 30%-65% off. Examples of steals: the Proenza Schouler bustier sheath for $450 (retail $1,950), the See by Chloe Fuchsia Ruffle Girl dress for $173.25 (retail $450) and the Halston Heritage party halter dress for $103.25 (retail $295).