Q: can I purchase a charger for my ibook 4g

apparently there are a plethora of chargers available... you might find google - ibook+charger+walmart convenient - ÇÇÇ

A similar charger for PowerBook G4 would likely be adequate for similar processor series iBook G4.

There are plain looking non-Apple replacement AC adapters that perform similarly to the original in

that they do work, but do not have the color light in the end to indicate charge/battery status.

OWC macsales, powerbookmedic, and other known vendors could be places to inquire; and as

stated, you may locate a suitable one of generic basic design locally, perhaps even at walmart.

Here's one just like a spare I was given with a G4 PowerBook, seems to be well made...

•NewerTech 65W AC PowerBook G4, iBook G4/G3: ($25)

http://eshop.macsales.com/item/NewerTech/APLPBI65W/

open box same as above (limited quantity $19)

http://eshop.macsales.com/item/NewerTech/APLPBI65WOB/

Since I've had several portable Apple computers, and desktop models, I try to keep extra parts

on hand; and have found working power adapters, airport base stations, and other Apple parts

in second hand stores for impressively low prices. Display adapters, & others, too. Even when

not in need of any, I look anyway. Spares are always good; they may also be trading stock.

Good luck & happy computing!