Look what I found - Maybe I could use an old android phone with ICS and use Wi-Fi Direct to transfer files:
Wi-Fi Direct Service Discovery
Ice Cream Sandwich introduced support for Wi-Fi Direct, a technology that lets apps discover and pair directly, over a high-bandwidth peer-to-peer connection. Wi-Fi Direct is an ideal way to share media, photos, files and other types of data and sessions, even where there is no cell network or Wi-Fi available.
With Jelly Bean, Android takes Wi-Fi Direct further, adding API support for pre-associated service discovery. Pre-associated service discovery lets your apps get more useful information from nearby devices about the services they support, before they attempt to connect. Apps can initiate discovery for a specific service and filter the list of discovered devices to those that actually support the target service or application.
For example, this means that your app could discover only devices that are “printers” or that have a specific game available, instead of discovering all nearby Wi-Fi Direct devices. On the other hand, your app can advertise the service it provides to other devices, which can discover it and then negotiate a connection. This greatly simplifies discovery and pairing for users and lets apps take advantage of Wi-Fi Direct more effectively.
With Wi-Fi Direct service discovery, you can create apps and multiplayer games that can share photos, videos, gameplay, scores, or almost anything else — all without requiring any Internet or mobile network. Your users can connect using only a direct p2p connection, which avoids using mobile bandwidth.
This info is on the Jelly Bean release notes website.
