Welcome to Basenotes Delphinium- that's one of my favorite flowers.
I'm not familiar with Ecusson but I have bought another scent from Long Lost Perfumes and found the quality to be very good. & a good reprroduction.
eBay is hit or miss because it depends on how old the bottle is and how it was stored. If it's very vintage the topnotes might be off, but the heart and base OK. If you can pick one up for a reasonable price, go for it.
Perfume Intelligence database shows Ecusson's (1952) notes as A soft classical floral aldehyde edp with notes of violet leaves, geranium, Sicilian lemon, cassie absolute, ylang-ylang, carnation, rose, jasmine, iris, vetiver, oak moss, vanilla, sandalwood and musk. Discontinued (date unknown)
Long Lost Perfumes (1995) Re-launched of the above.Discontinued (date unknown)
The Orlane version (1946) Discontinued (date unknown)
Good luck in finding scents you love! Sniff in good health!