Nocommotions has released three budget plugins for help when colour correcting in FCPX. Very reasonably priced, they range from $2.99 to $6.99.
There are many ways that plugins for Final Cut Pro X can be purchased and installed. Some companies use a sophisticated management system like FxFactory, some use installers from disk images and some just supply the standalone Motion effect file.
Template Master from Nocommotions is slightly different. It's a free downloadable application from the Mac App Store that allows the in app purchase of individual effects.
Just added to the app are three new effects ranging from $3 to $7 that help with colour correction.
Colour Picker ($2.99) This is based on an “Effect Template”, it creates a large solid colour area in the viewer based on an area chosen by the editor. The large area can be adjusted in size and position allowing it to be isolated and/or easily seen on the various waveform monitors for adjustment on the exposure/saturation/colour board.
Broadcast Safe Pro ($6.99) This is also based on an “Effect Template, it’s a broadcast safe filter that cleanly cuts at 0 & 100 IRE without adjusting the image. It also has some adjustment controls making it of great use for quick colour work and with looks supplied with FCPX or from 3rd parties that are “Motion Template” based rather than “Colour Board” based.