First of all, as far as I know, Ivy can only be obtained from the arena honor trade. This gives F2P players a chance to get a 5-star hero for free. This is a comprehensive guide on how to get a 5-star Ivy, as well as some tips for raising 5-star units from scratch in general. It's gonna take a looong time.

Ivy wasn't included in the notable units list because I didn't have any data on her. I'll add her in later.

Honor points consumed to evolve to 5-star : 900,000

900k honor points will get you either 180 Ivy Fragments/2.25mil gold/75 Roy Fragments.

Time taken to get enough fragments for 5-star : 36 days

For MAX-LIMIT BREAK: 5-star × 4 = 144 days

Gold cost for 5-star :

• 3-star -> 4-star = 300k × 3= 900k
  
• Double limit break 4* = ??
  
• 4-star -> 5-star = 800k
  
• Cost of leveling = ??
  Total: AT LEAST 1.7m
  

Total evolution materials (excl.dupes) needed for 5-star:

• 3-star -> 4-star = (3-star×1, 4-star×2, Magic Dust×20)×3
  
• 4-star -> 5-star = 3-star×1, 4-star×1, 5-star×2, Illusion Dust×20
  Total: 3-star×4, 4-star×7,5-star×2, Magic Dust×60, Illusion Dust×20
  

Amount of EXP required to make Level 60 Ivy = 739692

• lv.35 4-star×3 = 145690 X 3 = 437070
  
• 4-star lv.35 -> 60 = 448312
  
• EXP gained when limit break approx. 72845 X 2 = 145690
  

Total = 437070 448312 - 145690 = 739692

Amount of EXP required to make Level 50 Ivy = 639150

• lv.35 4-star×3 = 145690 X 3 = 437070
  
• 4-star lv.35 -> 50 = 202080
  

Total = 437070 202080 = 639150

Things to note (This applies to all 5-star units):

• Evolving to 5-star AFTER limit breaking twice costs 100k more EXP, but you end up with a Lv.60 5-star unit.
  
• However, if you start off with a Lv.50 5-star unit, it costs around 370k EXP to level up from 50 to 60.
  
• Therefore, it's much more efficient to limit break first.
  

That's not all.

• EXP gained when using a Lv.50 dupe to limit break at 5-star: 260747
  

• EXP gained when using a Lv.60 dupe to limit break at 5-star: 445424

• Fusing a Lv.60 into a Lv.70 for limit break will immediately max it out up to Lv.75.

• Fusing a Lv.50 into a Lv.70 for limit break will not, it will require an additional 170k EXP to max.

• In conclusion, limit-breaking even your limit-break fodders is EXP-efficient.