In 1998, LEGO released 4 Service Packs Technic sets, all of these sets have been retired. For that year, the total price of all retail sets cost $28, today those sets are valued around $46, a growth of 66%.
Most valuable 1998 LEGO Service Packs Technic set
5225 Technic Geared Motor $22.99
Highest growth 1998 Service Packs Technic set
5295 Steering Accessories +144.11%
Largest 1998 LEGO Service Packs Technic set
5294 Toggle Joints and Connectors 60 pieces
4 sets

5225 Technic Geared Motor

Theme / Subtheme Service Packs / Technic
Year 1998
Pieces 1
Availability Retired
5225 LEGO Technic Geared Motor
Retail $15.75
Value $22.99
Growth  +46.0%
Annual growth 2.8%

5226 Technic Assorted Cross Axles

Theme / Subtheme Service Packs / Technic
Year 1998
Pieces 18
Availability Retired
5226 LEGO Technic Assorted Cross Axles
Retail $3.99
Value $5.63
Growth  +41.1%
Annual growth 1.9%

5294 Toggle Joints and Connectors

Theme / Subtheme Service Packs / Technic
Year 1998
Pieces 60
Availability Retired
5294 LEGO Technic Toggle Joints and Connectors
Retail $3.99
Value $7.74
Growth  +94.0%
Annual growth 3.3%

5295 Steering Accessories

Theme / Subtheme Service Packs / Technic
Year 1998
Pieces 12
Availability Retired
5295 LEGO Technic Steering Accessories
Retail $3.99
Value $9.74
Growth  +144.1%
Annual growth 3.2%