It's definitely an interesting question!
Unlike a lot of collectibles, Disneyana tends to keep its value, at the very least, and a lot of it tends to increase with enough time. So, barring a huge global collapse, or really bad buying decisions, you should be okay as far as not losing your money. How much profit (in trade or cash) you make is the iffy part, and depends largely on trends. I don't know if anyone saw the PTD or Beloved Tales trends coming...
While some people seem to do okay making money at pins, I doubt you'll get rich doing it. However, it is nice to sometimes recover some of your expenses, or to fund your hobby with smart purchases.
In regards to whether or not you should actually spend that money that way, or just buy what you want...the answer is to do a mix. It's always best to get a pin as close to retail cost as possible (obviously). So if something on your Wants list is retail (whether from Disney directly, or sitting on Ebay), I'd pull the trigger...especially on low edition pins. Same for pins you think will make good traders.
As far as older pins that you Want...that's trickier. I have gotten some AMAZING Grails through trading, and saved a lot of money doing so. Pins I bought at retail from Disney (especially from ds.com) have gotten me the bulk of my Collection. But sometimes, trading is like having two hay stacks searching for each other's needles. In those cases, when you find a Grail (ESPECIALLY an old and HTF one), and it's at a competitive price, it's important to spend the money there. Don't forget- prices spike and dip all the time. At one point in time, my favorite Grails were going for $300+. I was able to get them for around $100 a pop, and one of them for $66. Sometimes, playing the waiting game is good. It can also shoot you in the foot (as many Princess collectors will tell you right now).
Summed up- if a pin that you just have that gut feeling about is close to retail, grab it and sit on it for a while! But don't be scared to get your Grails if they're a fair price (just don't over-pay for traders).
Next, in talking about buying trades now, in hopes that they'll increase in value and be able to get you HTG pins...I usually consider a few things:
-Is the pin in high demand/anticipated and/or of a low edition size/rare?
-Is it from a hard-to-get location or event?
-Is it a popular character or theme?
-Is it a good design or eye-catching?
Sometimes, my gut knows right away if a pin will be a future grail-level pin (like Art of Ariel). Other times, they can surprise you! But don't be too sad if you trade away a pin that later skyrockets in value. Because chances are you have a pin in your collection that you traded for that also skyrocketed, and that trader is kicking themselves for THAT trade. :lol: It's the circle of life, and in the end, it all balances out.
So- in conclusion to this rather long-winded reply to your questions....
-Yes, you should stock up on some good, solid traders. You can get some amazing trades that way.
-However, you should always take your budget into account (don't over-extend yourself)
-You don't have to falsely inflate your prices like the pre-sellers do. If the pin is good, it will speak for itself
-But sometimes it might take a while
-Finally, don't get discouraged if a pin you get doesn't take off like you expected...it's a balance.
One you didn't expect will take off instead. No one is 100% right all of the time.
Urk. Sorry if that was rambling. It's 6 AM over here...