This is a pretty easy strategy and I have found it helps me a lot more.
The general idea is that you have NO 100% item build. People might say how do I min and max then? Or I am going to waste money! Think of this as DGs Hire Purchase scheme.
The idea is that you don't know how a game will play out over the course of 30mins so you invest early, your return is that you will control other DGs a lot quicker than they can control you, paying for the loss in resale.
Reasons for flexible item buying :
* You have to return to health crystal or retreat before you have X amount for that item you want. If you save your money, you are going to have to come back again, either losing valuable time or burning 500GP anyway in TP scrolls.
* Saving for an artifact like Ashkandor will cost you time, if you are not winning by a large margin you are placing a large risk, what happens if the other team lock down the artifact shop, your gold is worthless.
* 5 full slots of cheap items can often be way more effective than one expensive item. The only exception is when you can sell a couple of items and get an artifact early.
Key to flexible item buying, is :
* Knowing your items, there are lots of guides on items, read them and study the shops.
* Knowing your build, do you need to be speed, mana, HP, armour heavy etc. Don't save for Ashkandor if you are Sedna support build.
* Removing your need to save up that last 3000 for X item.
* Removing your dependancy on what are thought to l33t items, there are plenty of viable choices that will give you an earlier edge.
* Remembering that you can sell items, so you are really only losing a minimal amount. This is especially important early on as you can fill your slots up with cheap items, be a lot more effective and sell them with maybe 500 GP loss for the lot.
* If you have consumables remember while you are staring at the gold counter you can sell one or two to make up that 300 difference rather than waiting.
Some examples :
* Early game you come back to get the gold or exp upgrade. You have 500 GP left over, get the Guantlets of Brutality, you will "lose" 80 GP on the purchase, but you have 25 extra damage a shot. The same goes for armour and boots, they WILL give you the edge early game.
* You retreat back mid game, you are stacking a couple of cheaper items and a couple of l33t items, you have 4K cash, you can sell your banded armour and upgrade it to Platemail Armour. You now have 4 times HP regen over the banded. If you get a kill while wearing it, you will make up the cost when you sell it. You still have 5 minutes of play before you can buy an Artifact, now you have maybe 6 minutes but with +20HP regen.
* You have 4K to Ashkandor, but if you sell your Slayers Grips you have enough for the Unmaker. Then do it. Getting an item like the Unmaker can make a real difference in those few minutes. Maybe you score a couple of kills, sell the Unmaker and get the Ashkandor.
When not to do it :
* There aren't many times, but obviously you don't want to be doing this for minimal gain, the point is that you have full cheap items at early game, full mid-high items at mid game, then high-artifact level items at end game. So don't upgrade your slayers wraps for Doomspite grips. 
