You will only be offered subscription plans that correspond to your existing usage of E-junkie. The $5/mo plan allows up to 10 products, so if you already created more than 10 different products in Seller Admin, the $5 plan would not be available to you. You can delete products to qualify for lower plan levels.
Some plans (like our $12 plan) are for tangible goods only, which means you cannot use digital-delivery features such as File Download, Send Codes, or product-specific Redirection (the latter is normally used to redirect buyers to a paid-content area of a site after payment). If you have configured any of your products to use any of those features, then the tangible-only plans will not be available.
If you would prefer to use a thank-you page on your site instead of the E-junkie thank-you page, and if you also want to qualify for a tangible-only plan, you can disable any product-based Redirection settings and instead set a Common Thank-you Page URL (in Seller Admin > Account Preferences) that is the same for all your products.