A cell phone is by far the easiest way.
If one of your parents has a compatible cell phone, perhaps you could purchase a memory card for it (what ever it takes - micro SD, Sony Memory Stick Duo, etc.) and a memory card adapter so that you can also connect that memory card to your computer. That way you don't have to use the phone's internal memory to store the downloads.
Alternatively check out used phones from ebay. I purchased a used one on the compatibility list for $25. The account for the phone had been cancelled, so I can't use the phone to call anyone, but I can use it to transfer download files onto my Tamagotchi-iD L. (I can also use the phone as a camera.)
Neither of them does . Also they wouldn't want to "waste" as much as £25 on a "little toy" such as a Tamagotchi. My mom was like "but you can't buy a phone just for THAT!" and "surely you can do without them!". The furthest I've gotten so far is my dad ordering a USB IRDA adapter, which will detect the Tama but when I try to sendd the downloads my Tama either refuses the download (why?) or my computer says "the requested address is not valid in its context".