I actually took a bit to go research this and look at our parts manual for this unit. The tech, unfortunately, is correct. There isn't a "projector bulb", per se, but I did check to see if the light source could be replaced without replacing the panel, and the answer was no.
The lamps in today's LCDs are CCFL backlit (or in some case, Edge Lit or LED backlit), which now has its own assembly, and allows the light source to be replaced. Most effective would likely be the LNxxBxxx LCD series, both in terms of repair and cost effectiveness. EdgeLit LCDs can be repaired, but it's a precise technology, and LED backlit may be considerably more expensive. I don't have figures handy, but I would imagine the CCFL-backlit LCD would be the most cost-effective repair. I appreciate your comments, and wish there was a way that I could earn your business. However, I have no ability to either fix the panel or refund the service charge.
Many 50", and even 56" panels can fit in a 50" wide width, but I'd definitely recommend bringing along a tape measure, as the size of the bezel may determine that.
I own a Samsung LTN406W LCD TV that has developed dark smudge-like vertical streaks in the picture after just five year's use. The tech Samsung sent to my house ($150 for 15 min. on the job!)told me immediately when he looked at the TV that it was not repairable, because the projector bulb and panel are one unit in this model. I was not aware that some LCD TV's were built this way and thought the projector bulbs in all of them could be replaced when they started to fail. I am currently shopping for a replacement flat screen TV no larger thn 50"W by 30" high by 4.5" deep that will fit in my plasma lift console. Which current Samsung models are the most repairable (ie. have replaceable projector bulbs)and have the best repair record? While I doubt I'll buy another Samsung, I thought I'd give you a chance.