It looks like fondant or white chocolate wrapped around each tier painted to look like wood...looks like some kind of icing under the wrapped tiers. Maybe she just really does not know how to execute a cake like this? Good luck finding someone who can! Hope this helps.
That is a Kaysie Lackey cake - so it isn't something you would just 'knock up'
This is a 'high end' cake and would require skill to get it looking like this - You would be looking at $7+ per serving and a minimum order of $300 (that is for ALL cakes not for 1 minute suggesting this would be the exact or even 'hypothetical' price.
If this is for your own wedding cake I would say LISTEN to your baker/caker - I admire somebody that states up front " they don't know how to make it or has no idea how it is done" - she is being HONEST with you ! A lot of people will accept orders and give no thought as to how they are going to fulfill them. BEWARE of those.
The last thing you want on your wedding day is another episode of ..... This is the cake the Bride wanted........ and THIS is what she got !!!