What and when is a good time/method of buying tech off the market for an indy?

I am grasping the indy build slightly but can tell I'm still utterly noobish. I'm feeling okay with my BPT/private market/and grabbing but I've not found out a strategic point/advantage to getting tech.

I make my own to account for high prices first few days, then buy on late Friday on out, I'm playing CI