try aiming for a ers 210, they usually go for only a couple hundreds $s a 210 was my first aibo, i now have a 210 and a 31L pug.
theyre more expensive yes, because theyr enot out of preduction, but when they were new robots, they were around a grand. this is because they really are top notch in consumer robotics. they really do make pleo just look incredibly stupid in comparison in terms of AI.
aibos have hundres of words and phrases they understand, they have proper vision, obstacle detection, colour recognition (pink is toy, orange is a colour it dislikes etc etc) they actually learn from environment and human interaction. eg, my 210, who is now 3 years old, when he was a baby, was hopeless, and even when he was more 'grown up' he was more withdrawn, with more nteraction, and praising behaviour you like to see, scolding what you dont like so much they get a more defined personality. my 210 is now very much a show off, and prone to mood swings etc etc.
not totally dissing pleo, he is a cutey! but hes no patch on aibos AI, and aibos are now nearly 11 years old.
of course, what ive described is only for the older models ive had experiance with. the ers7s, are hella more brainy. with full on pattern recognition, and face recognition, short term memory for remembering where places and objects like his toys are, as well as being hooked up to your PC so they can play songs off it, or even blog online.
id say keep saving and aiming for an aibo, you wont be dissapointed; unless of course you want something more 'organic' looking like pleo. i dont really understand why some people dont like aibos looks. hes supposed to be a robot, not a pet.