I have to agree with Bloobell - there are so many good reasonably priced fabrics available for curtains that LA comes a poor second. These are probably names known to curtain makers rather than makers of other items, or on the high street. For example, Clarke & Clarke, StudioG, Prestigious, iliv to name a few.
Once you start using large panels for curtains then problems like inaccurate pattern repeat sizes, not understanding half drop repeats, printing off grain, printing right to the edge of the fabric with almost no selvege area, supplying lengths folded up in carrier bags, supplying large orders in multiple cuts without asking about drops, pattern dropping across widths and various other issues which get really stressful for the maker crop up regularly. Some of these are down to poor quality control and others to lack of staff training.
If your customer really wants fabric from LA then I'm sure you will be able to make her curtains, but be very clear with her that you will not be responsible for any problems with the fabric and don't feel guilty about adding enough to the price for at least an extra hours work to give yourself time to check the fabric for pattern repeat size, checking carefully for flaws etc. before you cut it. Once cut, they will not take it back/replace if you find a major fault later on.