My layout is going on 22 years now and the lighting has gone through several OK, MANY changes in that time. Fortunately, many of the existing fixtures were easily converted to LEDs.
I started out with several 2' x 4' fluorescent fixtures with the big T12 lamps and magnetic ballasts for general lighting and many track lights with 50W halogens and R lamps in them
My next phase was to "upgrade" to CFLs in the track lights (Yuk!) and T8 fluorescents with electronic ballasts in the 2 x 4s.
Even my LEDs have been replaced over the past year or two with dimmable LEDs. These have improved recently, some of the "early" dimmable models were not very good. The newest ones have a broader range of dimmability.
Here is a small sampling of my lighting arsenal:
I always keep an eye out for sales and closeouts and watch for fixtures at the Habitat For Humanity Re-Store for economically priced fixtures.
These recessed 3" cans were $5. each and they take an MR-16 GU10 beautifully.
Here is an overall view of part of the layout with the "work lights" on. The 2' x 2' panels are LED thin panels and the 2 x 4s are converted by removing the ballasts and hot-wiring the tubes. Some LED "tubes" wire with a hot and neutral on each pin at one end, others have both pins at one end hot and neutral at the other end. Some work with the ballast left in place but I MUCH prefer to remove the ballast.
And here is a similar view with the LED MR-16s lit:
On the "other half" of the layout room I use more track light fixtures and some of these are MR-16 GU10s and medium mogul PAR 20s.
Home depot was closing out those neat goose-neck lamp holders. They came with 50W halogens but a MR-16 is a direct replacement.
Like Mike, I get many of my LEDs from Amazon and some from a place called 1000 Bulbs.
I make inserts using white melamine paneling and the gimbal mounted 3" can lights snap right into a hole I make with a hole saw.
Sometimes the beam-spread is mentioned in the specs of the lamps but generally the spot is pretty tight, this can be used to an advantage, too, if you want to highlight a particular scene.
Hope this helps, Ed