Who dropped the price? The cheapest full kit I know from hidplanet runs $390 shipped, including projectors. I hope you're not talking about some kit that XenonDepot or XenonKing or whoever the hell they are sell, because those are aftermarket rebased kits (not OEM parts) that don't come with projectors and are generally regarded as trash.
For a good pair of shrouds and bezels, tack on another $75. Then you have to figure in miscellaneous costs like paint to black out a housing to reduce glare, JB weld, all the electrical components like fuses/relays/wires to build your own wiring harness. At BEST you'll be slightly under $500. Show me where you can do a full retrofit for $300 (and I'm not talking about getting some fantastic one-time deal off eBay or some other private sale).
Oh let's not forget the clear lens that you have to pull off a pair of crystal clear headlamps if you have fluted lens and don't want your new hids spreading light in random places because of them. I didn't even include that cost.