Have you tried The Ordinary oils boffy? Not as sophisticated as Decleor but good quality oils and very inexpensive.
I only buy them when they are a few pounds a bottle. I must say oils last forever. the Christmas TSV lavender/iris oil I am still using it every single day..got about aanther weeks worth cant complain. plus since I have been using Decleor my daughters keep saying how good I look. so once I can get a good deal I will keep using