Robot for beginners

Hi all! I'd like to build my first robot and, essentially, these are the things I'm interested in:

1) to make some experiment with programming the robot's behaviour 2) to use different kinds of sensors (e.g. ultrasonic, infrared, bumpers...)

But, at the same time, I'm looking for something which is not too difficult to build (I can program software but have never built a robot!), and not too expensive!

So far I've found these 4 alternatives: A] Asuro:

35 Euros)

B] Boe Bot:

90 Euros)

C] Picaxe microbot (about 60 Euros for the standard version - without sensors)

D] Kranius:

120 Euros)

What is your opinion? Which one do you suggest me to buy? Why?

Thanks everybody, Zark