SPST On-Off Pushbuttons

A quick check of my Mouser catalog shows some
Stock # 642-A010X for starters Then add the LED and Screen Total cost - about $27
OR 117-MP45/1E1RN012 only about $15
Is that enough to get you started?
Howard Garner

They exist, but you'll likely pay through the nose for them. Here's a link to alternate action (push on/push off) pushbutton switches at Mouser. This includes illuminated and non-illuminated. Use the menus to refine the search for the type of illumination, contact type, and terminals that you want.

An auto parts supply house is one source, but they will look funny, what with fog-lamp symbols on them and such, and they will cost you loadsadough. Another source would be a shop that specialises in supplying commercial control panel parts, such as are used in factories, IT distribution panels, etc. These are also pricey, but come in many colours and sizes. The yellow pages or an acquaintance in the electrical business will guide you to the source. I googled "control panel push button suppliers", but most of the hitt were manufacturers in India and China.
Much cheaper alternative 1: SPST (or DPDT) bat-handle switches - the position of the handles will show power on/off. You can paint one or both sides of the handle some bright colour(s) to increase visibility.
Somewhat cheaper alternative 2: wire LEDs in parallel to the track power.)(1) You'll need a dropping resistor to prevent the LED to fatally overindulge in power. If you use different colours, one will indicate eastbound, the other westbound. Handy. Or obsessive. ;-)
(1) This wiring in parallel is done at the control panel, you don't need to run extra wires to the track itself.
Cheers,
wolf k.

Farnell seem to have dozens of varieties for a range of prices starting from a pound or two and going up to L10 or so.
I started by typing `illuminated switch' into the search box and then using the parametric refinement. Useful search terms probably include `latching' and `push on push off'.
SPST, DPDT and so on refer to the number of poles and whether the switch just opens and closes or whether it switches between two sets of contacts. SPST = Single Pole Single Throw; DPDT = Dual Pole Dual Throw etc.
Farnell have a minimum of L20 for ordinary credit card orders.

You dropped a number in the part#, it's 642-A0101X. And there are much cheaper ones available - just type "spst lighted" into the search box and you'll find four good results. *