here are my comments:
Trophées de la Guerre de Succession d'Espagne 1700-1713 par Pierre Fouré
£60 original (looks excellent)
Pierre Fouré is (or was - I don't know if he is still alive) an exert on Louis XIV's period, history, uniforms etc. He published in studies on his own - including an excellent one on the first French dragoons. This work is well known and is very good.
Fallou L. Le Garde Imperiale
£45 (this didn't seem to have as much detail as I was expecting, is it worth having?)
There are no complete studies of the Imperial Guard and no rceent and exhaustive ones. Given the price I assume this is the reprint done by Olmes in the 1970s. It is all of the B&W texte and images in a convenient format. The color plates can be found in LCV's reprint of Marco Saint-Hilaire. Overall Fallou's remains the best study to date - based on Perrot and Amoudru's etc. He did not get into the archives and find new stuff. For this price it's worth it.
Les Aigles Impériales et le drapeau tricolore 1804 1815 Jean Regnault
£70 this looked good, but errm the price?
I saw some postings comparing Charrié's work and this one...well, I really don't see the point as tehse are massively different works. First of all Regnault was a student of Hollander and Charrié a student of Regnault ! So, this is a continuing thread of research...Hollander probably did the best and most exhaustive studies but they never covered all the topics (e.g. his study on the flags of 1812-1815 is simply amazing, but he wrote almost nothing on 1804-1812 !).
Hollander seemingly was part of this class of people who was wealthy enough prior to WW1 to work off their revenue and spend all their time doing research (Marmottan, Cottereau, Glasser were all like that !). Regnault and Charrié did not have that luck. Regnault was a career officer interested in history. His first work was "moblisation et concentration pendant la campagne des cents-jours" - published in the late 1930s it is a remarkable study on the gathering of french forces for the hundred days campaign. Some of his senior officers would have been better off reading it it in time for 1939 !
His work is really more a detailed history of French eagles than a book on how the flags looked like. It makes wonderful reading if you're good enough in french.
Charrié's work is a complement of it as it describes in detail the flags. It is only a minuscule portion of the work he has done on this topic - but it's worth every penny. I recommend you do get a copy from LCV as once those copies are done with, it will be definitely out of rpint, and before LCV found a pile of them that had been forgotten...it was fetching prices around £200 !
HISTOIRE DES GARDES DU CORPS DU ROI pendant la période révolutionnaire 1789-1801
£25 also looked good
LA GARDE CONSTITUTIONNELLE DU ROI dite Garde Brissac
I do not know either of the above but the title are inspiring for anyone interested in the early part of the revolution
LA GENDARMERIE FRANÇAISE EN ESPAGNE ET EN PORTUGAL - Martin
£35 I think
A great study reprinted by terana and availble from LCV - if it's an original copy just rush for it. Lots of excellent text about these units (including the lanciers-gendarmes)
Eltings complete uniform set £500
I assume this covers the 4 volumes - a steep price, but Knötel did do wonderful work - the only issue is that tehre is no reference. He did go for sources which in many cases have been lost - or in some cases can now be challenged (Forthoffer's sources have never been proven). The first two volumes are very scarce.