Well .... a s13 (180sx and silvias 91-98) red and blacktop are the same motors. Stock they will push out about 205 and yes it comes with turbos. Prices range from 2600-2800 plus shipping.
S14 motor pushes about 220 HP has variable valve timing system (VVI) its like a V-Tec but for nissans and better turbo setup (ballbearing) prices range from 3000-3400 plus shipping.
I wouldn't bother getting a S15 motor its gonna cost some money about 5000-6000 for that price u can just buy a s13 upgrade the turbo and it would make the same power.
All those prices are for front clips not just a swap so keep that in mind. I see alot of people sell crap online so becareful! Just because its cheap somewhere else don't mean u are getting a bargin it could just mean u are getting what u paid for it! (Cheap Crap) !!!
Here is a good site to get swaps (Nissans,Hondas)
www.autowerksmotorsport.com
They buy a container of clips from japan every month. I highy Recommend these guys!!!!! Honest guys they don't lie to you and they will send a picture of the clip u'll be getting before u even buy it so u know what ur getting! They sold over 500 swaps last year!