Our aim is to provide a cheap solution for small businesses in need of an ecommerce solution.
So we try to avoid having paying plugins for everything like you find with many other shopping carts.
We indeed received a few requests for PayPal Payment advanced and it is on our todo list, like 50 other payment plugins requests.
And so, we're adding payment plugins to HikaShop in almost every release of HikaShop... With 2.1.1 we added the Ogone plugin which is used by all banks in Belgium, with 2.1.0 we added the PostFinance plugin which is used by lot of people in Switzerland, in 2.0.0, we added the PayPal recurring payment plugin which is used a lot for subscriptions...
We are currently working on two other payment plugins (amazon, MIGS VPC pay) and we're improving all the payment system in HikaShop to handle multi payments.
Nevertheless, here are several developers out there already developing payment plugins for HikaShop so why not ask them to see if they could develop it for you ?
For example, webIT has developed 5 payment plugins for HikaShop recently and they have a special page on their website to request payment plugins:
www.webit.bz/-i-14.html
PolishedGeek has also developed payment plugins for HikaShop and you can ask them.