I agree with your assessment that 4K isn't ready (or affordable) yet. Consider what you want to shoot, and what you're willing to carry around to do so. Then find a 1080P camera within your budget.
As already stated, the total resolution isn't as important as the sensor size/quality, lens quality, in-camera compression (the less the better), and stability/ease of use.
A benefit of 4K: you can zoom & crop a 4K wide shot to give you a close-up if you plan to output 1080p. Nice for commercial productions still outputting 1080p (capture establishing shot & zoomed shots simultaneously & blow things up w/o loss of quality)... But for family vacation movies & stuff it wouldn't serve much of a purpose unless you plan to edit the footage extensively.
Also as alluded to in an earlier comment - what are you watching the video on?
There are very few 4K screens out there at the moment. You'd have to edit & reduce the resolution anyway in order to view it ... Or also buy a 4K TV and computer monitor in addition to the 4K camera. For that, you could buy a nice 1080p camera plus your kid's 1st semester of college :)
Finally, capturing all the footage now & saving it until 4K is more widespread means having to store really large raw video files you can't watch at full-res in the meantime anyway. You'd also need to purchase more external hard drives, more memory cards, and probably a Blu-Ray burner with discs for backup. 3-4yrs from now that might not even be compatible technology.