Welcome!
You will be subject to some "sticker shock" after your 20 year hiatus. Freight cars that were in the $3 to $4 range have now mostly broken the $10 barrier and many cars are in the $20 range. But those Rapido couplers are just about gone now.
You might consider at least "window shopping" on eBay for some used equipment if you're really on a budget, but you do need to be careful about what you're looking at.
And of course I recommend the Unofficial Micro-Trains Release Report for reviews of Micro-Trains (you might know them as Kadee Micro-Trains), but then, I am a little biased. Nearly all of the top N scale dealers subscribe to and read my column, so I don't think it would be fair to single any of them out specifically, but chances are you'll be happy with most anyone that's recommended to you here. Price, service and availability of product are the three key attributes, others would add web-friendliness as well (nice site, easy to order on line).
It is still a great hobby; it's even better than it was in 1986 (20 years ago)!