Why printer cartridge price is half the price of my printer?

2 cartridges = Printer + 1 cartridge

because of Research and Development Cost, will the cost go down in the future or it will remain the same or it is just a standard price.

The printer companies make VERY little profit on the printers. They do that to get you hooked. Nearly ALL the profit is in the cartridges. They are very cheap to produce, yet they charge as much as they think they can get away with. They hate it when you use refilled ones, & put scary warnings not to do it in the instructions. Standard price. You are stuck buying them because refilling a cartridge doesn't work well. The lack of internal pressure from refilling can make small type and such unreadable as well as the excess ink leads to smearing.

If you print a lot and don't mind black and white only you may want to look into a basic laser printer. The cost per page printed is massively lower than an ink jet printer. Most reviews of even the lower end office laser printers will have a cost per printed page listed. Because printer makers are capitalists and want to make money. They know you need ink and want to rape you while you buy it. If you use a refill kit, they will find a way to reprogram the cartridges or printer so that it won't accept the "used" cartridge because "it's bad for the printer." In reality, refill kits are only bad for their bottom line. It's like Polaroid cameras. They practically give the camera away so you will want to buy plenty of Polaroid film at a buck an image. Once you own a printer, you are going to be back again and again for ink...