(The previous version of this post contained incorrect files in that the transistor package was EBC instead of CBE. The board wouldn't let me correct but only delete the post -- hopefully not much harm was done yet.)
@mredeker and other interested parties,
Attached to this post are the complete design files in Eagle CAD format for a possible implementation of a transceiver for the RPi and LIRC. (The tar.gz is really tar.xz, I guess this forum isn't really configured for sharing files the type and size needed for this stuff, so I had to make a few unorthodox moves here.)
The only safe way to do the transmitter part is to use a separate power supply for the IR LEDs (you can't know in advance what PSU will one drive the RPi from) so it runs off two AA batteries. This is the safest bet if you don't know what you are doing, electronics-wise.
The board itself is designed so that it can be glued (with hot glue or double-sided tape or whatever) on top of a 2xAA battery holder. The only thing one has to make very sure of is that the driver turns the transmitter off after it's done sending, or else smokes will puffs. On the plus side, the design provides pretty good range. One may solder the LEDs a bit bent so they are turning away from one another a couple of degrees for increased radiation angle. Soldering should be a breeze even for the unexperienced (all through-hole components and plenty of clearance between them).
The CAM files can be sent to Seeed Studio for manufacturing (about $15 for 10 boards shipped, or 20 boards if someone panelizes the design); or possibly any other PCB manufacturer, but the Gerbers were generated with Seeed's CAM rules. The other components should not cost more than a couple of bucks in one-off quantities.
BOM is on the schematic.
For reference, here are the schematic and the board layout images (download them for full size):

- Schematic
- rpi_lirc_transceiver_sch.png (24.99 KiB) Viewed 15986 times

- Board layout
- rpi_lirc_transceiver_brd.png (13.44 KiB) Viewed 15986 times
I have also sent Áron an amended version of the schematic that is up on his site (he's yet to publish them) that has actually been built. That one runs off the RPi entirely, range unknown, also the only thing there is to be said about that one is that it runs with my RPi off my power supply. You are much better off using the battery-powered version.
No warranty, also I will not be monitoring this forum in the future. Good luck with your transceivers.