Walmart offers the Bell Sports Overpass 300 3-Bike Compact Folding Trunk Rack for $29.94. Opt for in-store pickup to avoid the $5.99 shipping fee. That's the lowest price we could find by $20. It features padded cradles, a 6-point attachment system, and folds down to 14.25" x 6.5" x 4.75".

Note: Amazon charges the same for Prime members, but it's on backorder until April 16.