Remember, the fundamental, slowest and most expensive problem in software has nothing to do with tools or productivity - it is knowing that you are building the right thing. Everything else is easier than this.
As far as improving the velocity, you have to know that there are obstacles, then what are they, and how can you remove them, and can the $1000 be used to do this? If there aren't any obstacles, what makes you think the team can increase velocity?
A lot of things which cost almost nothing can improve the environment: reducing pointless meeting requirements, taking out phones, improving stakeholder involvement, etc. All the best practices have been covered in the literature: PeopleWare, Mythical Man-Month, Code Complete, Writing Solid Code, etc.
$1000 won't go far, but it will start a library, so I think books are your best bet. I would let the developers decide how to stock the library. I would also give each developer a marked part of the shelf where there own personal favorite books can be stored, just like a bookstore where the people recommend their favorites. There is also the possibility of Safari subscriptions or ACM or IEEE memberships which come with digital bookshelves.