Getting a custom flag would require several considerations and decision making to get the best deal for your intended desire and purpose. Things as simple as color, fabric type, and layout design are some of the more important things to take into consideration. Another thing to consider with the former is the location where the flag would be displayed. For example, placing your flag outdoors for public viewing would mean that you have to consider getting a fabric type that is quite heavy and durable to withstand the changing weather.
The quality and durability of any fabric used for flag making rests mainly on the weave and the number of ply it is made out of. The most common range of plies flag fabrics are made out of are from 1 to 3, with the latter being the thickest and most durable, but relatively more expensive than the other variants.
There are pros and cons of differing number of plies for flags, which is mainly a tradeoff between price and durability. Single ply flags may be printed with the same layout design but would have the backside bleed with the print. This makes the back side unusable. This type is best used when the flag is placed against a wall where only the front side is utilized.
Three ply flags are basically two single ply printed layers placed against each other with a middle second layer as a buffer. This eliminates the bleeding of the printout from being seen on the other side. It may serve as a full view flag on both sides and may be displayed as such, but is relatively much more costly.
As a good measure, it may be wise to visit online retail shops of custom flags to gain some feedback from other customers and also second opinions from helpdesks.