Grow your own from certified seed it's cheaper as most of the seeds will germinate and give you rhubarb towards the end of this years season . Champagne or Victoria are decent seeds to use . Think my 18 seeds cost me £ 1.35 eight years ago . Every one became a decent crown ready for planting out .
Plus & a big plus at that is that you will not be importing pests in a crown into your garden . It also gives you time to make up a deep well manure bed for the baby plants when they are about six inches high .
PS
Split & move the crown after every fifth year after last harvest to a new deep manured site ..it helps to prevent crown rot & stops disease build up like honey fungus .
If you don't move to new well manured ground after 5 yrs the plant may live to 10 yrs old but you wont get good crops.