I'm thinking of getting a raspberry pi to do some scraping work so i can go out while everything continues to run while at home. Is there any reason why Scrapy would be a bad idea for a Raspberry Pi setup? Potential issues i was thinking would be WiFi speeds, performance, and system requirements.
There is no particular limitation on the pi with regard to network connection speeds, wifi or otherwise. You'll get whatever your adapter provides.
I'm sure the pi will be able to keep up parsing html as fast as the internet can realistically deliver it. Maybe it will start to fall behind if you are doing it with local network data that can be accessed consistently at very high speed, or the scraping is very convoluted, but in general the pi is probably ideal for this.
From the looks of the "scrapy" page it is pure python, portable to linux, and shouldn't pose a problem requirements wise.