You will find many examples of designs that fit your suggested scope (costing less than buying ready-made) at Instructables, Hack-a-Day and Make's own site in addition to many electronics-based designs at Adafruit, Sparkfun and other similar sites collecting user-designed concepts.
You mention robotics, which can be created using inexpensive controllers like the proprietary but inexpensive Raspberry Pi or fully open source designs Arduino or BeagleBone controllers (depending on the level of comlexity you need in the project). I explained some of the details in these options when teachers in the STEMulate Learning and SOLID Learning programs selected the standard electronics platform (http://www.stemulate.org/2013/06/01/solid-learning-microcontroller-options/
) we would use in building 3D printable materials for educational lessons if that helps. My teachers and workshop participants selected servos for their robotic designs because they are inexpensive, easy to source, relatively precise and can be driven directly by a microcontroller like the Arduino (http://www.stemulate.org/2012/07/04/solid-learning-servo-robot-actuator/
In writing the upcoming book "3D Printing for Dummies" with Richard Horne (@RichRap), we had the opportunity to look over many different types of 3D printers, with low-cost options like Quentin Harley's Morgan (partial Polar design), Josef Prusa's latest i3 (Cartesian) and Richard's own 3DR (Delta configuration) that can be easily created for less than $500 USD (Quentin is trying to get the Morgan under $100 USD total build cost now). Richard has adapted Rostock-like movements to use less costly alternatives like braided fishing line instead of toothed belts for his 3DR printer to make the design easier to source and less costly.
I think you will find many individuals in the broader Maker community more than willing to share their ideas and open source designs for low-cost projects that any new entrant can build atop to get started without costly equipment or grand makerspaces already stocked with a world of tools. If hte nearest such location is an hour away, it might be time to find a few others in your area and start having meetings in someone's garage or at a school to build interest in a local makerspace you can create.
The folks at the Maui makerspace in Hawai'i or the ATX makerspace in Austin Texas did something very similar to this in setting up their first locations around local maker interests. There are many different opportunities to meet like-minded makers around the world (http://www.scoop.it/t/maker-stuff
) and you should take every chance you get to visit local makerspaces and hardware hacker groups when you travel.