It appears that you are asking about disc printing, primarily. Printable discs do not have an adequate surface for true high-res printing, like photo paper does.
Nor do the printer driver settings allow true high-res disc printing. In short, you can spend as much as you wish on a printer, but discs will come out looking much like they do on a $100 printer.
Rather than spending more money, spend some time learning about monitor calibration and printer driver settings, color profiles, etc, and learn to get the most out of your printer. The Canon IP4500 uses 1 pl droplet technology that is unsurpassed in much more expensive printers of any brand. Expensive 6 or 8 color printers will not produce sharper looking discs, though colors may be subtly improved. (again depends on proper system and printer calibration)
You’re already using the best printable discs available. Though it’s good to note that there is a huge range of intensity in the white printable discs, and the best results are obtained with the brightest coating. For a more subtle, matte-like finish, and I think a bit more resolution, try some Verbatim Gloss. Though the Verbatim is not as true a white as the TY.