Some of the sheds do quite a wide range of mouldings, but none of them seem to display the sections they might have so going online doesn't help there, as you've doubtless discovered before coming on here in desperation!!
And, of course, the chippies on here will make their own.
I have occasionally bought the simpler "hardwood" mouldings (sold alongside the pine) because it's quicker (and therefore cheaper overall) than cutting them down and machining them out of oak stock, and they stain OK to be 'got away with', but on a quality job I'd do them myself out of stock.
Try to get pine to look like oak and you'll end up with pine trying to look like oak.
Have a word with your local joinery shop? But I suspect the cost will surprise you. You could always do a back-scratching deal with him