I recently bought the Kmart 2400w bagless vacuum! I have been interested in this because previous hype that this can replace a dyson, and having had the pleasure of using a dyson multifloor vacuum with a powerhead, I wanted to write a quick head-to-head comparison.
On initial inspection the external design appears similar, but the Kmart build quality is definitely poorer with cheaper/flimsy materials, the tube is thin, the connections between parts is similarly loose.
I was surprised that even though the external design appears similar, and Kmart's branding of a 'bagless' vacuum with 'cyclonic technology', that in fact the filtration system is very different. While dyson has minimal filters and uses their patented cyclone technology to filter particles, Kmart's vacuum uses a series of filters ending in a cyclone that traps dust in a container: 1) HEPA filter (does not appear to be a true-HEPA filter), 2) main filter, 3) foam filter. This surprised me because externally the kmart vacuum appeared to have a set of cyclones at the top, but it's just an external design choice to appear similar to the dyson vacuums (there's just a single cyclone created by a plastic spiraling part to direct the dust into the container). The design is less original, but it still is very effective at trapping the dust. This is important because while it is similar in effectiveness when you buy the vacuum, Kmart's design suffers with long-term losses in suction/filtration. Reviews suggest that this is the case with a life of ~6 months - 1 year. I find that there's more TLC needed with the Kmart vacuum filters, needing to wash/clean them often (extra 15-20 mins). I expect that the filters will break down over time.
Powerhead: the dyson powerhead is electric, with wiring through the tubing supplying the powerhead. In the Kmart version, the powerhead is passive. There is an internal wheel (similar in concept to a waterwheel) that uses the vacuum's suction to turn the powerhead. This means 2400w of suction is not 100% utilised as some suction is used to move the head. Some reviews suggest a loss of suction after a month. Unfortunately the motor unit is hidden so I can't comment on the motor itself (whether it's a motor issue or if it's a powerhead/filter issue). I can understand why this is a big problem, because if there's no suction even the powerhead won't work to bring up hairs/dust trapped in the carpet. Thankfully for me, the vacuum is functioning properly. I'll update the review if there's any loss of suction.
Usability: let's nitpick. The power cable is shorter than your typical dyson vacuum, thinner, and always seems to get stuck under the motor unit. The tube also cannot extend! Result, I'm always having to yank the vacuum to go forward or turn. There is noise, but it's comparable to a dyson (probably quieter actually because the dyson powerhead can be quite loud).
edit: I've been really happy with dyson's support centre as well. Previously my dyson powerhead stopped working and the support centre asked to look at it, and ended up replacing the powerhead/cyclone unit/tubing with a new unit. Improvements in suction for 1/4 price of a new unit. Though I know that if you're not happy with your kmart vacuum you can always try to return it for a refund.
TL;DR - you get what you pay for. $95 at Kmart, you get a vacuum that sucks well and traps lots of dust. However with the savings, you are hit with poorer build quality, minor design issues, a questionable longevity, and extra filter care. I am satisfied with my unit because of its ability to remove dust/hair and am willing to put up with it, but if we're comparing it to a dyson, I would still recommend the dyson. Save your money.
Really great review. Thanks for taking the time to type it out. Not on the lookout for a new vacuum but I'm sure others will find this helpful.