Expedia, Travelocity, Orbitz review: Pricing

Using the online system, a vacation package price jumped 100-400% after the last step (return flight).
Package for 2 from DTW to Salzburg 4/28 - 5/6. Das Essigmangut Hotel. Price $1,094pp. Select no cancel/no change fee departing flight - Price $1,174pp. Select no cancel/no change return flight - $1,174pp. Final price $3,402pp.
Same problem on all three sites although pricing difffered