As posted many times on other threads, UPS/FEDEX oversize rates jump tremendously when the box exceeds 130 inches, length + width + girth. That's a small to medium bike shop box. The larger ones commonly available at the LBS will exceed that limit. The larger boxes will still be within limits but at a MUCH higher rate. Traveling by air? Box size may not be so much an issue with many airlines.
Bikeflights is cheaper than the UPS store but not immune to these limits. Their rates will also jump when box goes past 130 inches. From their website...
https://www.bikeflights.com/dimensionsandrates
"To get the most economical shipping rates, your “Shipment Size” should be less than or equal to 130 inches or 330 cm"