You really dont need any of that for building simple robots. The most important utility would be a multi meter, one should cost around $20 - $40 for measuring continuity and voltages (some measure resistance, capacitance, measure transistors as well).
An oscilloscope is really a luxury at hobby level. You could also just use batteries instead of a benchtop power supply and a function generator is just too far.
Id spend the money on components. If you get the axon microcontroller designed by the admin on this board, it can be programmed with an oscilloscope program (also created by a member of this board). letting you use the axon and a computer as an oscilloscope. that way you get a microcontroller which you really need for a robot and the bonus of an oscope that doesnt cost anything near what an standalone oscope would cost.