There are plenty of them available on eBay for about $150. https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1311.R11.TR11.TRC2.A0.H1.TRS1&_nkw=surface+pro+3+lcd&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=surface+pro+3
Or even as low as $120 if you don’t mind waiting for delivery from China. Someone posted about having problems with ones from China but I afraid that even the ones from the U.S. were made in China. I’ve replace mine twice and both worked fine. Both times from physical drops and not part failure.