How to flip Serum 207 (3) in OSRS

Flipping Serum 207 (3) on the Old School RuneScape Grand Exchange currently makes about 5 gp profit per item after the 2% GE tax: buy near 31 gp (the instant-sell price) and re-list near 36 gp (the instant-buy price).

• Buy at (instant-sell): 31 gp
• Sell at (instant-buy): 36 gp
• Margin after 2% tax: 5 gp (16.13% ROI)
• Buy limit per 4 hours: 2,000
• 24h volume: 12,713 (very liquid)
• Max profit per limit cycle: 10,000 gp on 62,000 gp of capital

The flip, step by step

1. Place a buy offer at or just above 31 gp (the current instant-sell price).
2. Wait for the fill. Serum 207 (3) is very liquid right now, so offers usually fill within minutes to a quarter hour.
3. Re-list at or just below 36 gp (the current instant-buy price).
4. The GE takes 0 gp tax (2%) per item when it sells, leaving 5 gp profit each.
5. Repeat up to the buy limit (2,000 per 4 hours), a full cycle is 10,000 gp on 62,000 gp of capital.

Margins move constantly. Re-check the live Serum 207 (3) numbers and price chart on GrandExchange.com right before committing.