It all depends on what you need at the time.
There are times when an inexpensive ready made frame is just the ticket for presenting artwork. Occasionally you can find a great bargain in browsing through a frame shop when they are marking down items for a sale.
If you have a custom mat cut for the artwork, the final effect can be quite presentable. In the example illustrated below, the artist needed a frame for one of her first public displays and the frame on the left served quite well for many months.
One shortcoming of the original framing which was not considered at the time, was that mats were not acid-free and the framing system did not provide long-term protection protection against humidity, dust, and insect pests.
The piece was reframed using acid-free materials and conservation framing techniques which provide a sealed "sandwich" of art enclosed between acid-free foam core and protective glass with plenty of air space between the art and the glazing.
A larger mat and a burl wood frame with touches of gold to complement the colors of the artwork brings out all of the beauty of the original art without overwhelming it. Incidentally, both images were photographed without glazing to eliminate distracting reflections. In the actual framed piece, the glazing gives the piece highlights which complement the art.
The burl wood moulding uses hand assembled wood veneer to provide a richness and complexity of design that perfectly complements the pastel drawing and the subject for the discriminating collector. But, there are many other moulding choices which would have made for a similarly striking effect at a lower price.
Custom framing enables you to select from a wide range of options for every piece of art to get the results you want and still stay within your budget.