I like the SL-8, but you gotta be able to stand the sight of watching a big, gaping hole burn through your wallet as you try to modify it.
Quoted for truth.
My little misadventure so far:
SL8 - $2399
2 extra mags - $135
Mag well adapter - $185
H&K soft case - $190
H&K 3 point sling - $60
ESB2 battery assist - $35
Extra rail with iron sights - US$179
3x optic with carry handle - US$350
G36K forearm with heat shield - US$120
Picatinny rails for G36K forearm and stock forearm - $130
IEA MIL-Optic muzzle brake - $260
H&K G36 FBI lower - US$285
Push pin and roll pin for conversion - US$42
G36C stock with cheek piece - US$185
CNC machined aluminum stock block conversion - US$295
Eotech 552 HWS - $595
FAB T-Pod foregrip/bipod - $175
Misc P-mags and LAR mags - $170
Which, at today's exchange rate, brings my total to just shy of $6000, plus various taxes and shipping. You should be able to get some of these parts used (which I did, this is a few hundred more than I spent), but also bear in mind, you'll have a difficult time finding many of these parts in Canada (particularly the G36 parts - forearm, stock, conversion block, lower).
That said, it's truly a thing of beauty to me, and I love it, but yeah, be prepared to be poor, do a lot of work, do a lot of looking around for parts and trying to deal with import/export BS from the States, and general hard work.
If you want something out of the box without all the work, if you have the money, go with the Swiss Arms PE90, and if you don't have that much, go with a used AR180B, SL8 (and don't have plans on converting it), or an XCR.
I think I'm going to go and cry myself to sleep now.