I definitely want to buy a tree but I didn't want to kill it or butcher it.
I started with the same sort of fears and it is not a good emotional state for bonsai. You must get over it.
I began with an air layer of one of our landscape acer palmatums. Next I dug a cotoneaster that we didn't want in our landscape any longer. I bought various landscape nursery plants, usually ones in poor health that were sold cheaply in 'lemon sales'. I killed a few but still have most of them and from those experiences I have learned a lot, but most importantly, how senseless most of my original phobias were. I admit, it also helps to have a 'pricey' nice tree at the same time.
Even if you are made of money, I think you should have a year or two of this kind of experience under your belt before you start spending real money on bonsai (BTW you may find it interesting to view the past and current BNut 'Box Store Challenges'). But another bonsai journey route that is open to you is to go to special sessions at one of the country's bonsai professional's nurseries (e.g., Bonsai Murai, Cretageus, Boon) and spend thousands on one of their trees which the master will attend to on your behalf for a small fee.
Regardless, buy species that interest you and that are suited to the environment where you are going to keep them.