Like bed pillows, you pay for quality fabric and what they are stuffed with, but especially you pay for the designers or stores name and mark-up. If you buy them custom made you are also paying for the seamstress's time to make them.
Some people think that the more you pay for something the better quality you get. Not always true.

I have never bought a decorator pillow in my life. This is one area where you can save and get what you want if you sew. Besides if you paid big bucks would you ever want to change them, or would you be stuck with them until they wore out. I think I would.

You are right. Yours probably look as good as any you buy and the bonus is you could match them to your table skirt.

Agree with "oilpainter" especially does not mean they will last longer or wear better or you do not always get what you pay for.
Few of the things that maybe different, in addition to the cording/piping, they usually have been stuffed in an inner muslin pillow and may have foam wrapped in batting before encasing it muslin to keep the shape, they have hidden zippers so cover can be removed for drycleaning, most are not washable.
When making overstuff if they are used to rest someones head, it keeps the shape of the pillow. If they are the just the "Show Off" type they will last for a long time.
I have actually purchase some cheap bed pillows and used the stuffing for some of the pillows I have made.
I usually do not slam a product but do not use that NuFoam, it is actually almost the cost of foam, it does not hold up. Hope this helps.