Purchase Gadgetron PDA from 'Steve' is a mission in Ratchet & Clank. While exploring the Gorda City Ruins, Ratchet found a booth ran by a "Steve McQwark", who offered to sell him a Gadgetron Personal Delivery Assistant. Ratchet did not buy "Steve's" disguise, but nonetheless did purchase the PDA.
Start from the central plaza and use the Magne-Strip on the left to move onto a floating platform, which takes you to a new region of the city. You must climb on top of a raised area here, which is covered in ice and surrounded by deadly electric fences, and make your way to a gap in the wall on the other side. Keep to the left end as much as possible, as a strong gust of wind will quickly blow you off, but if you time it correctly, you will safely access the intended path. Now use the Magneboots to move along a twisted Magne-Strip, being patient to avoid the mines rotating around at fixed intervals. You can destroy the mines with the wrench, and you will not take any damage from doing so.
Upon stepping off the Magne-Strip, carefully skate across a series of ice-covered platforms, dodging electricity from fences and gaps in the floor. Be wary, as Clank will not be here to arrest your momentum. Repeat this on the other side, after which you must use another Magne-Strip to reach the next area. Again, the floor will be covered in ice, but this time, a lone plasmabot and minibomber will prevent you from continuing. If you stay still, you can dodge the former's attacks by making timed jumps, whereas the latter is harmless if you stay out of reach. Once cleared, head to a small ledge behind the plasmabot's spawn point and jump up to grab onto the yellow wall.
Using ledge grab, you must climb to the center of the ice path in front of you, noting the strong gusts of wind from behind. Jump up and keep sliding to the right, while making timed jumps to dodge the electric fences (as the wind propels you at great speed), to try and reach the platform to the right and at the end of the ice path. Once cleared, go and talk to "Steve", who offers you the Gadgetron PDA, which starts the actual mission, and after buying it, promptly ends it.