Honest advice here: DO NOT BUY ANYTHING UNLESS YOU NEED IT. Plan a week ahead. Order just what you need to complete an objective. Don't be afraid to throw discrete components and things in the trash either.
I have literally just spent two years clearing out about 100kg of component stock I've collected over the years because I nearly tipped over the line. I'm down to literally nothing now and I buy on demand. I've only kept some weird shit that's virtually impossible to get hold of on demand and some very basic discrete jelly beans. Why:
1. It causes mental burden lurking there which is depressing.
2. If you're not careful you turn into a crazy batshit hoarder obsessive about holding on to it all. I dropped a DMM off at someone's house near me about 2 years ago I sold on ebay. The guy had drawers on all walls in a 3 bedroom house, including the hallway and part of the kitchen. His wife had left him because of it and he had devoted his life to filing and cataloging crap. Sure he could find a 2W carbon comp 510K resistor or an obscure tube like "that" but there were at least a million components in there that were going to end up in a skip and years of his life gone. He admitted he stopped doing projects because when he got older it became a burden to look after it all.
3. You can never find what you want anyway unless you super-organise it and you turn into Mr batshit above.
4. You have to catalogue it all which becomes a consistency issue and a chore.
5. You probably aren't going to use all the items so it's a false economy plus if you don't buy 2000 of each value shitty hair legged resistors from China, you can afford a few good ones. Same with ICs etc. I used to shudder at paying 10 GBP for an IC but if I hadn't got 11 tubes of 74ls04's I could afford to just buy the damn thing and shrug it off.
Find a cheap supplier who does small quantities, write up what you need, buy the parts, do it and then clean it away.
Edit: apologies for sounding like a crazy person
What you say here is true..and many, many times, I have seen this hoarding of components first hand. Nothing more depressing than a filthy garage filled with dusty parts that never got used in anything at an estate sale. Do NOT be that guy.
That said, after years of working both professionally and on my own projects in electronics, I would definitely have been crippled in the following activities without a reasonable stock of parts:
-prototyping
-repairing
-experimenting/learning
I have limited myself to a certain fixed volume of space in which I can store engineering objects, and this has worked okay. I've also sub-limited that space into fixed volumes for things like resistors, switches, wire, vectorboard, logic IC's, transistors, etc..all the "categories" have their own fixed box. I have not collected more than these fixed areas and I do like to throw stuff away when possible.
Looking back, having a WIDE assortment of the following has paid off and I use these parts the most from my immediate stock:
-through hole and SMT resistors and capacitors
-through hole potentiometers
-transistors (bipolar and mosfets most importantly, through hole and SOT-23)
-diodes (low Vf schottkys, small and big power silicon, sot23)
Having SOME of the following has been important, although a wide assortment was not needed
-basic logic like NAND and schmitt trigger inverters, CMOS wide supply range is very handy
-switches (toggle, pushbutton, AC capabale)
-relays
-voltage regulators
-LED's and photodiodes
-inductors and transformers
And the following have proven over the years to not really be that important:
-microcontrollers/processors (usually projects involving these need a specific part number and/or package and having some random one on hand isnt useful)
-obscure logic
-uncommon transistors
-smt parts that would not be useful for quick usage because of extremely small size or dense footprint (tssop parts are not fun to hand solder, SO or bigger is still useful though)
-displays (projects using a display arent in a rush and choosing a specific display is probably more efficient)