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- Ninja Forms (free, highly recommended by StudioPress) - https://ninjaforms.com/
Free with add-ons purchased individually
$49 Paypal Express (1 site)
$49 Layout & Styles
$49 Conditional Logic, etc.
$99 Personal package (1 site; BUILDER PRO PACK: Layout & Styles, Multi-Part Forms, Conditional Logic, File Uploads + 20% off Additional Add-Ons)
$99 + $39.20 (20% off) Paypal Express = $138.20

- Caldera Forms (recommended on Genesis WP Slack & FB Intermediate WP group) - https://wordpress.org/plugins/caldera-forms/
Free version = Most Free Features Of Any WordPress Form Builder
Caldera Forms Free includes conditional logic, calculation fields, multi-part forms, file uploads and column layouts out of the box. 
$164.89 Individual (includes Paypal)
$74.99 Paypal Express (can use with Free version) This looks like the best option!
$99.99 Paypal Pro

- Gravity Forms - http://www.gravityforms.com/ (includes conditional logic)
$59 BASIC (1 site) 1st year/$50 per year after that; BASIC
$159 PRO (3 sites; includes Paypal Standard Add-on)
$259 ELITE (unlimited sites; includes Paypal Payments Pro Add-on)
25% off at WP Beginner http://www.wpbeginner.com/deals/gravity-forms-coupons/)

NOTES ABOUT PAYPAL EXPRESS vs PAYPAL PRO
PayPal Express checkout for PayPal allows for one time payments via your PayPal account or credit cards. All payments are completed by redirecting to PayPal and then returning to your site.

PayPal Pro has several payment options and involves no redirects. With PayPal Pro you can accept credit cards using Caldera Forms credit card fields, or via a PayPal account using PayPal Flow.

- WP Forms - https://wpforms.com/
Constant Contact integration built in and available with free version.
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- Contact Form 7 (I don't like this; on some Genesis demo and client sites; however, resource-heavy) http://wordpress.org/plugins/contact-form-7/

- Secure Email Service (non-WP, not a plug-in): https://www.hushmail.com/hipaa-email/