Integrated transformer is usually for when you have very little space...or your volumes are very high.
There is more development time with integrated transformer.
Also, it will need gapped core.
Gapped cores can be a pain if your qtys are only small.
(gapped cores are common for little flybacks. but less so for the bigger cores.
Ill send you a doc on how to make a integrated transformer for LLC if you want?
High cost for trxformer is the "planar transformer", but again, if your volumes are high, then its ok.
Obviously the more coils it has, the more the labour. And tape windings are more expensive (flat windings)....since there is more labour in there termination.