A few comments.
Very unlikely you will find a used suit for your build. Also most sales are for smaller sized suits left over stock. You are tall, may be an issue depending on where your length is. You could possibly be into a custom suit.
Where are you located? Are there any race shops near you?
Most regulations require a 1 piece suit. Stick with that.
Highly recommended you get somewhere where you can actually try on a suit. Different makes in same size are not always the same.
Spend as much as you can on the lightest coolest most comfortable suit you can buy. More layers is better in protection even when rated equally. My older 3 layer Sparco Xlight is cool enough I can add a layer of nomex underwear and still be more comfortable than many lower cost 2 layer suits.
If you have a harness, buy a HANS.http://www.apexperformance.net/Suits_c_36.htmlhttp://www.ogracing.com/driver/suits?suit_rating=1204
Leaf is a Canadian company so you may be able to order a custom suit from them and get a cost break on the exchange rate. Get the template for sizing from them and go to a local tailor and have them measure you. http://www.leafracewear.com/index.asp