Below is a complete (sort of) list of the parts used in Panda Monium, plus the approximate costs of them to us. This may help others in construction or planning, and it provides a way for us to feel guilty about the cost of the robot!
Panda Part Quantity Where from? Total Cost (UKP)
Sinclair C5 Motors 2 Adam Harper 260
NCC Speed Controllers 2 4QD 180
Joystick Interface 1 4QD 16
Hi-Tec 6-Channel R/C transmitter, receiver, 4 servos plus ni-cads and charger 1 Model Aerodrome 110
7AH 12V Sealed Lead Acid Batteries 12 Bull Electrical 192
15AH Sealed Lead Acid Charger 2 Maplin 72
Sheets of Polyethelene 6 Chris' brother 0
Steel frame chair (chassis) 1 Crediton Tip 5
Dead petrol mower (wheels) 1 Crediton Tip 5
Sheet steel, 1mm 2 Rose Autos 15
Sheet steel, 2.5mm 1 Crawley Metals 25
Steel fence post (main spike) 1 Wickes 5
Cable (various) lots Halfords 20
Sheet steel, 4mm 1 Chris's house 0
Mild Steel Axles 3 Electromail (RS) 9
Steel bearings (with housings) 4 RS 76
Timing Belts 3 RS 10
Pulleys + hubs 2 RS 40
Failsafes 2 Hobbystores 22
18VDC motor 1 Bull Electrical 23
Timing Pulleys + belt 2+1 RS 25
Mini car jack 1 Mini Clubman 0
DPDT switches 2 Bull Electrical 2
Microswitches 2 Bull Electrical  2
Cold Chisel Spikes 2 France 4
12mm MDF 2 Wickes 12
Low current control cable lots Old Video 0
Grand Total To Date (5/10/1998) - - 1130
It's probably fair to say that some of these sources were not the cheapest, but we used them because they were convenient for us or quick to order from (eg Electromail). There are definate ways to keep costs down, for example, by using HiTec rather than Futuba R/C gear, using Bull batteries and making use of local refuse tips. We didn't find car boot sales to be very productive, but they are a good source of tools if you need more. Remember also that things like nuts, bolts, screws, connectors, drill bits, grinder blades, etc all cost money - and you will go through a lot of them.