Yes. "A decent price" might involve some soldering, but it's worth it.
Search eBay for "DC 12V 5050 SMD" and "G4" or "Bayonet" or "1154" or whatever type of lamp base you are trying to replace. You will need an LED with about eighteen 5050 SMD chips on it to get the equivalent light output as one 18W 1154 lamp.
An 18W 1154 lamp puts out about 250 lumen. An 18 LED module puts out about 290 lumens and consumes only 3.6W (20% of the incandescent).
http://www.ebay.com/itm/G4-5-9-13-18-24-26-6-SMD-DC-12V-3528-5050-LED-Light-Warm-Pure-White-Bulb-Lamp-/121049963692?pt=US_Light_Bulbs&var=&hash=item1c2f23dcac
In my experience having the LED's shine in only one direction still shines around the rig due to the diffraction of the housing lens. In my opinion, 270º light output won't put out as much useable light...the reflectors in our 12V fixtures really aren't that stellar. Lens good, reflector bad. haha
