Easy in the fact that a visit is only required once every 3 years. It is the easiest tax residency to hold.
Cheap, well, that depends on you. If you have a law firm do it for you, you'll probably pay around 2500 USD to get it done, plus of course the costs to make the visits and accommodation in Asuncion. The fee itself isn't that high - around 400-700 USD, but relocation firms need to make a living somehow. Then, it's about 3 months to get the document issued︀ (or you can give the governmental office an extra 300 USD to get it done︁ within 2 weeks).
You also need to send in your blank VAT filings (otherwise you︂ won't get a tax residency certificate), or pay an accountant to do it, which will︃ be like 500 USD yearly. They are empty (in most cases), because Paraguay has a︄ territorial tax system, and you don't pay anything on what is earned in Paraguay. For︅ the revenue in Paraguay, it's 10% income (for person and for corporate). The VAT is︆ also 10% on Paraguayan income.
Keep in mind that Paraguay doesn't have many double taxation︇ agreements, so if it is of any use to you depends where you live. Paraguay︈ also doesn't have any CFC regulations. A company not in Paraguay and not selling to︉ Paraguay with you as the tax resident will not be liable for the 10% tax︊ rate.