I have been buying BitUSD at the moment by using the profits that I made from each profitable trade that I executed at Bittrex. During the last couple of days, I was day-trading an alt coin called Greenbacks(GB) on Bittrex and I was using the GB trading profits to buy BTSX on Bter. after that, I withdrew the BTSX that I bought with the GB trading profits into my Bitshares X wallet and once those BTSX arrived in my wallet, I immediately bought BitUSD with them. I wanted to do it this way since 1.) I made some profitable GB trades on Bittrex and 2.) I already had some BTSX in my wallet but I did not want to use the remaining BTSX (about 500+ BTSX left) in my wallet to buy BitUSD because I had already sold a lot of BTSX for a good profit during the run up to buy PTS and I wanted to keep the remaining 500+ BTSX that I bought when the price was under 2000 satoshi/BTSX.
EDIT: My BitUSD purchases on the BitSharesX wallet decentralized exchange went very well and I had no issues at all. I am satisfied with it.
EDIT 2: I bought my first small amount of BitUSD at 20.75 BTSX/USD level and then again much later when the level was at 24.97 BTSX/USD.