If I look for an LM13700 in DIP format from US vendors on eBay, I find I can buy one for $9.95 (shipped) or I can pay $7.95 (shipped) for a “pre-owned” part.
On Amazon I can get 10 for $9.99, with Prime shipping, from a vendor with 11 negative reviews out of 133 for the past year; one comment in their feedback: “These devices are not new. They are previously used devices. I’ve attempted to use 5 of them, 2 have been DOA.” Or from another vendor who charges more and has a similar feedback rating. They’re the only Prime vendors I can find for this part.
Or I can wait until they’re back in stock at Tayda (for about $2 each), or I can get them at a similar price from DigiKey, whose lightning fast turnaround I have already mentioned. I don’t actually need any immediately, so I’ll see if Tayda’s stock arrives in the next few weeks.