Wrong! A lawyer is necessary of course, but an US company is NOT. In fact, it's totally the opposite. In cases where the product is entirely produced outside of US borders (producing includes manufacturing the product, doesn't matter if it's physical or virtual like software + customer support/maintenance), you are not liable to any tax. Now, the selling part is a bit problematic and it depends on the specific case, because technically selling is not producing, so you don't have to pay taxes according to the law, but more often than not, you will have to. I will give you 2 examples:
1) You are selling a SaaS (software as a service) product and are meeting clients in the US to close sales, especially if the price is mid XXX to 4 figures per month. You are also maintaining an office in the US to handle sales and/or customer support. In this case, leveraging the tax directive I mentioned above is not possible and you will be liable to tax. Even if you don't have any offices in the US and are just coming to close sales and then leaving (say with a tourist/business visa or ESTA) and customer support agents are located outside the US, you will still have to avoid the
Substantial Presence Test and while most countries have a simple system of not being in the country for more than 180 days, US of course has a different system (hell, they even measure their shit totally different than the rest of the world, so of course you would expect this in taxes).
You can read the formula in the IRS page I linked. Best option in such cases is incorporating a company in Cayman Islands or any other offshore island - lots of headache and you will definitely need a good and experienced lawyer to tell you what's the best option for you and how to implement it.
2) You are selling a virtual product, closing sales online and are not maintaining any offices in the US at all. In this case, you pay 0 taxes to the IRS. You pay taxes based on the system the country where you incorporated your company has. Territorial taxation is of course the best, because you pay only for services/goods sold within that country's territory. This is the reason why you hear Hong Kong & Singapore being talked a lot as offshore options to incorporate your company, especially if it's an online-based one.
There are also lots of other cases completely different and in-between. I mentioned these 2, because I have experience in them. I am not a lawyer, but I have met with few of them and everything I told you above can be confirmed easily. However, in any case, I
strongly recommend you to contact a lawyer ASAP as your country of citizenship, double tax treaties, etc... might affect your case. Choose a lawyer that knows a good deal about International Law and is experienced in such tax issues. I'm also assuming that you don't have an US citizenship, otherwise that will complicate things 10x more.
Anyway, your business model (and dropshipping in general) can be included under case 2 in most circumstances. That means you don't need a company in the US. You only need to incorporate outside in a tax-favored country. That will also allow you to use local merchant accounts in those countries - maybe not the best, but definitely better than PP. Also, 2Checkout is a trusted global company, but be warned that they don't handle disputes/chargebacks very well unless you have very clear and specific TOS, which you should. Their $25 fee might kill your profit margins. I have used them for SaaS though and never had any real problems.Other merchants include: Authorize.net, Stripe & Bluepay (not all are global though).