Appears the unit of choice is a dual impression US/CS unit. Since the 17th NY was a Zouave unit, as others have mentioned I would highly recommend conversing with members of the unit itself to determine their sources, and proceed accordingly. Finding items on the open market may or may not match the requirements within. Some Zouaves have same/similar items... others had parts unique to only that given unit. Don't want to waste money buying things that have not been confirmed usable to the group. Go for the correct items the first time. Zouave uniforms are typically something not generally stocked on the rack of most sutlers or makers. Might find used gear for sale otherwise most will have to have it specially made, which typically tends to be expensive with the level of work involved. The group may use someone that makes their uniforms that might offer a better price deal, worth checking on.
Noticed on the website provided they don't seem to have an alternate or generic Federal uniform as an option which is typically odd to find, that many/most Zouave groups do. Since there will probably be battle events they desire to participate in that the original unit may not have actually been at... So you have folks in Zouave attire running about a battle reenactment where the 17th or any Zouaves might not have actually been.... Most tend to have an alternate more generic impression at hand such as simple issued sack coats, sky blue trousers and fatigue cap, hence able to fit in and portray nearly anyone , or nearly anywhere needed....
The Confederate impression is that of the Palmetto Riflemen (Co. C; Palmetto Sharpshooters) which was an ANV unit. Depending on your intended desire and level of authenticity you wish to obtain.... This can become problematic on the impressions and authenticity view since they are portraying a unit what served with the ANV... but their participating schedule of events are mostly at western or deep south related events.... Same kind of issue of Zouaves at historically non-Zouave participated event... or folks with ANV issued uniforms and gear, also ANV issued flags at events that none were historically present at.... Many that habitually participate in both theater events will have established both an ANV and generic AOT impression respectively....
Bringing the