I do not want a vendor lock in
It may sound tempting to build everything in-house, but consider your long term strategy. Maybe you have a couple of great engineers now, but when the leave (and they will). How easy it is for you to hire developers? Did you build a culture for this and are you willing to?
The worst lock in is to your employees. When they leave, they have no contractual obligations to help you. Wheres, a vendor will have a contractual obligation to replace the employee without a time gap.
Fixed price contracts are less risky for me
Nope. Your vendor is going to include a risk buffer in his proposal, whether you see it or not. It may be anything between 10–30% and that is good money being put to waste. Also, they will include and charge for a Project manager (whether you see it or not) to manage the scope boundaries.
You will not have an Agile project and you most likely will not build trust with the vendor. It is 2019, you should really be working on Agile project by now. There are models to protect the budget and still work without a fixed price. One such way is the “capped time&material contract”. Ask me if you need more info on how to set this up.
I’ll choose my partner based exclusively on the CVs
Really? Are you choosing partners of employees?
Get to know your partners before you choose, meet them at their office. Some questions you should ask yourself: Do they deliver or do they just code? Have they delivered projects in difficult scenarios? Have they performed on my scale before? Do we have a cultural fit? Can they scale fast? Are the developers happy and will likely stay there for the duration of the project (what good are the CVs if they are temporarily available)?
We are an enterprise, I need an IT partner my size
Huge IT companies are usually not attractive employers for the most brilliant minds. They tend to dislike corpo cultures, but you probably already know that. Also, super small companies usually do not have project, communication and delivery processes ready for the enterprise projects. Look for a sweet spot where a company is strong enough to have solid processes, but still elegant and cool enough to attract the best employees. Companies employing between 50 and 300 would probably be a good place to look for.
I want only senior developers, this is a complex project
Let’s say we define a senior to be someone with 7+ years of experience. And let’s say you are looking for 3x Vue.js senior developers to build your frontend. Vue.js is only 5 years old at the time of writing this and has only reached a decent level of traction 3 years ago. That would mean that your senior developer might have 3 years in Vue.js and your junior 2 years. Would the double price difference make sense? I guess not.
You need seniors, people who have street smarts and can see wider angles. But be smart and cost efficient when it makes sense. If you are looking for a rule-of-thumb: 1x senior, 2x professional, 2x junior. Thank me later.