I think Creative made a pc card slot soundcard, and there are a few USB soundcards in your price range, but I think only the Asus Xonar U3 is the same form-factor as Creative's X-Fi Go! If you already have the X-Fi Go!, I read a passing reference that you get less static when you use a USB cable to connect the DAC instead of plugging it straight in.
Overall though, I don't think you can get great static-free sound out of a less than $50 DAC the size of the U3 and Go! If I'm wrong and you find something, let me know! Meanwhile, I'm happy with my Recon3D sound processor, it's portable enough for me and it was on sale last week for $69 shipped. Maybe it will go on sale again at some point, perhaps you put a price alert on it and save up till you can afford it? Head-Fi'er NamelessPFG might sell his. Here's my review: