Unless you go through someone like Warmoth, you will probably get very rough parts to put together. With an S-style guitar, that can cause some headache around the neck pocket fit without some necessary sanding or a shim. The frets will also probably need a level if you are not purchasing from someone like Warmoth, not to mention the sharp fret ends.
Even if you buy a complete harness with all the pots, switch, and jack, you will still need to purchase pickups and solder those to the switch. Difficult? Not really, but does require the purchase of a soldering iron. You also need to be careful soldering the ground leads to the pots, because a crappy soldering iron could cause you to overheat the pots and melt them, especially if you are using cheap pots.
Honestly, unless you are in it for the fun of building a kit, you are better off buying a used Mexican fender and then upgrading it over time, if you want to. Price wise, it doesn't really make sense unless you are willing to learn how to level frets, round the fretboard edges and round fret ends. You are just not going to get the same quality parts in a Mexican Fender for less than Fender. You can only go cheaper, and now you have a guitar that doesn't feel good to play, uneven frets, cheap parts, crappy pickups, and neck pocket issues.
I've specced out a Tele on Warmoth many times, and i'm always looking at around $1,200 before I even purchase pickups. Doing a quick reverb search shows Fender Mexican Standards can be nabbed easily in the $500's.
