Old topic but I'm also looking at the possibility of a custom build instead of an off the rack Sage. Crunched all the numbers and figured out that it was either go with the Sage CP3113 from Fred's Tackle or save $200 on a custom build (blanks can be purchased online for US$280). Only issue would be warranty if the rod snaps since the rebuild will cut significantly into any savings.
$280 US so lets say $300 CAN for a nice square number, probably about $35 for basic shipping. Now you're at $335 + labor to build the rod which is usually around the $150 mark, now you're at $485. Buy an OK reel seat at you're at or just over $500...
May as well buy a built rod it would be cheaper as you still need to buy eyes, butt box, thread, hook keeper & winding check (although dirt cheap even for the good ones) and any other flashy stuff that some people do like decals and add taxes still.
No point in buying cheap stuff for the build as it is not very easy to upgrade components later on and you're buying one thing twice. Better to just bite the bullet and buy good stuff the first time.