You bring up a good point.
The main reason to buy a printer like this is if you do a lot of printing, because you buy the ink by the bottle and just refill the tank when it goes low.
We purchased an older model, the ET4550 3 years ago. I think the price was around $380, on sale, from Costco. Since then, that printer has printed over 19,000 pages! Mostly school work for our grandkids. It also came with 'bonus' ink they said would last for 2 years, and the only ink we have purchased is one bottle of black ink for $20.
Some people will say it is an inkjet and they don't print as good/clear as a laser, but we were surprised at the quality of the printing. Inkjets have come a long way. I actually bought this printer that is on sale, and just received it yesterday. The reason why - my small laser printer that I hardly ever use and was purchased about 2 years ago is low on toner. To buy a complete set of toner cartridges, HP Brand is about $350. I opted to buy a new printer instead
So getting back to the cost of ink. A complete set of ink, Epson brand is about $50 and should print 7,500 pages of black or 6,000 pages of color. The printer comes with 2 years worth of ink if based on printing 200 pages per month
Lastly, it's Costco. You buy it, you try it out, you don't like the way it prints - you return it for a full refund - they pay for return shipping and will pick it up from your house