So, Jastrow's Aramaic Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature is the basic dictionary of Aramaic for a lot of scholarly work. Very basic. We had to use/buy it in my Aramaic courses.
The print versions are terrible to look at, and hard to work with. It languished on pre-pub for a few years, couldn't quite get there. Now it's been on community pricing hitting close to 60% at $20, less than the $50 it was on prepub for, and less than the Hendricksen reprint of the 1903 edition.
https://www.logos.com/product/16534/dictionary-of-the-targumim-the-talmud-babli-and-yerushalmi-and-the-midrashic-literature
Yes, there are better things out there (Sokoloff), but those are multi-volume and $$$ (as per this thread http://community.logos.com/forums/t/30138.aspx?PageIndex=1 ) and even less likely to make it into Logos.
And yes, you can get 89 pdf files of Jastrow, copies of the 1903 version... but it's not easy to work with at all.
So please, if you do any kind of Semitic work at all, throw on a $20 bid!