Hi Galan,
I really really really don't want to be rude but - why on earth do you want to make your own programmer ? If you build it then you have no support - so if it doesn't work then who do you call - Ghostbusters

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It just seems that if you want to create 'robots' that there are lots of other stuff to think about: motors, sensors, code, intelligence,vision, electronics, software etc etc.
I like living in a house: painting and decorating rooms to my own taste etc - but I don't want to buy bricks and cement and build a house - life is too short. Other people do that and they are much better at it than me. Equally I bought a soldering iron rather than making one. I also buy electricity rather than generating my own....... (get the jist?)
Spend the money on a programmer and then start making robots.
Once again - don't mean to sound rude but thats my 'humble opinion'.
Obviously there will be replies from people who have built their own programmer, or even house maybe, saying how easy it was and how they managed to save $30 but their prototypes blew up 10 processors before perfected.
So spend Saturday morning online to your favourite e-store to order a programmer. Then make a list of all the other hardware/chips you need for your robot shopping in the afternoon.