I am a relatively new tie-buyer but I've been buying at least a couple a week recently. Post-SF, I love ties so much I want to wear one every day.
I buy ties from thrift stores (here we call them 'op shops' ), eBay and from sales. I like 3.25" too, though I'll go a little skinnier and a little wider if I like the tie otherwise.
The most I've ever spent was AUD$33, and I don't think I'd ever pay more than about that. Why? Mostly because eBay is a tie goldmine, and brands like Lands' End, Brooks and Banana Republic offer exactly what I want for usually under $15 shipped.
Really, eBay is PERFECT for tie-buying: shipping is cheap; fit is not an issue; what you see is what you get; and because ties aren't that popular nowadays and last a long time, there's a massive oversupply floating around out there.
As far as colour and style go, I'm working on a collection of mostly blue, red and green, mostly stripes dots or solids, and some interesting textures like wool, linen and cotton.