Answered 2 questions :P

I know what you mean by trying forever to get the Santa and finally being able to do it.

I have had Santas off and on now for a few years myself but after the 8th or so time buying another one I decided I was going to save up for a purple partyhat. I actually had a purple back when they were only 50m-ish in like early 2004. I sold it just a few months later after it rose to 60m which was a ton of cash back than that bought me quite a bit of armour and 99 crafting.

So, I saved up for a few months and got the cash needed to buy a new purple but than I looked at my stats and was like "Hmm, I still have a few 99's I could buy with this cash.." I decided not to buy a rare but instead improve my character

Personally I have no future plans to ever buy a rare again, it's a tricky market and can crash in a matter of a few days whenever someone feels like crashing it. Basically, buy at your own risk.

In the end it's your decision but I wanted to put in my two cents. If you're wanting to build your skills spend your cash on that but if you don't than buy a rare, it all depends what you like doing in Runescape.