Finding good compost is a delight. Some of the stuff is not fit for purpose in my view and no way would I buy what I could not feel first.
I think various branches of chain stores and garden centres buy locally too, not a bad thing when it is heavy and costly to move about. If I am right then that could mean that a recommendation from a source in one part of the country may not be good stuff at another.
You could try to locate a local grower who grows on a wholesale basis and contact them about letting you have some of theirs. Delivery may be another matter altogether though. 100 litres is a very small amount and your cheapest bet could be to hire a taxi to get the bags back to where you want it from a local retailer.
If you are thinking of ordering in bulk for an allotment site then may be you can negotiate a discount or free delivery locally.
